
M^ICEr 

ONE* 

DOLLAR 


PtyCE 

ONE 

DOLLAR 


^TOPAGE. YACD AT THE- PPOCTOP QVARPY-CAECUFF .r«\D. 


BY- dEflROEr piHEKMAN Ab AAV 


ANDTft 


INDVW 













































Copyrighted 1911 

Entered according to Act of Congress by 

THE CAPITAL CITY NEWS SYNDICATE 

HARRISBURG, PENNA. 

The office of the Librarian of Congress, Washington, D. C. 













INDVW 


M^ICE 

ONE- 

DOLLAR 



i^lCEr 

ONE 

DOLLAR 




iTOPAGE. YAPD AT THL PBOCTOO QUARRY -CAPD1FF ,/AD. 

BY- dEDRGt 0LEERMAN • Ab-AM 























































Copyrighted 1911 

Entered according to Act of Congress by 

THE CAPITAL CITY NEWS SYNDICATE 

HARRISBURG, PENNA. 

The office of the Librarian of Congress, Washington, D. C. 


//A 

©CL A 2 92 4 85 






CONTENTS 


Foreword, ..„ 

The Story of Slate, .. 

Methods of Testing Slate, . 

A Notable Welsh Quarry, . 

Quarrying Slate in France, . 

Peach Bottom Slate, . 

Important Buildings Roofed with Peach Bottom Slate, 

Other Pennsylvania Slates, . 

Vermont Slates and Quarries, . 

Faults and Merits of Maine Slates,. 

Maryland Slates (Other than Peach Bottom), . 

The Slates of Virginia,. 

New York’s Best Known Slates, . 

Slates and Quarries of California. 

Arkansas Slates, . 

Georgia’s Slates and Quarries, . 

Tennessee’s Slates, . 

Quarries of Utah and the Salt Lake Region,. 

Arizona’s Only Known Quarry, . 

West Virginia’s Quarries and Slates, . 

Slate in New Jersey, . 

Minnesota Slate, . 

Characteristics of Various American Slates,. 

The Ideal Quarry, . 


The 

Page Stor y 

7 of 

j l Slate 

17 
24 
28 

32 

42 

47 

53 

57 

60 

61 

63 

66 

68 


71 

73 

74 

76 

77 

78 
80 
82 
86 


5 































INDEX TO ILLUSTRATIONS 


The Old Proctor Quarry, Cardiff, Md., From Which The Best Slates in The World Are Taken, 

(fid Peacth Bottom Mill, York Co., Pa., Showing Slate Roof 130 Years Old. 

Trimming Slate With Foot Power Knife at Proctor Quarry, . 

Slate Splitters at Work, Peach Bottom Ridge,. 

View of the Great Galleries at Dinorwic Quarry, North Wales, .. . .•. 

General View of Dinorwic, the Largest Slate Quarry in Europe, . 

'Phe Quay at Port Dinorwic, North Wales, Showing Slate Trains, . 

A Corner of the Rich Pennsylvania-Maryland Quarry on Peach Bottom ridge. 

Typical Quarry on Peach Bottom ridge at the Pennsylvania-Maryland line, . 

1 A he Owens’ Homestead, Cardiff, Md., showing Peach Bottom Slate Roof in Perfect Condi¬ 
tion After Half a Century, . 

Old Ramsey Tavern, Peach Bottom ridge (130 years old) a Striking Example of Indestructi¬ 
bility of Peach Bottom Slate, . 

Clearing Away the Debris in Quarry Near Slatington, Pa., . 

Remarkable Formation Near Slatington, Pa., Showing “Syncline” Crossed by Curved Joints, 

Curled-up Formation of Sea-green Slate in Vermont Quarry, . 

Slaty Rock Crossed by Quartz Veins in Green Slate of Vermont and New York. 

Peculiar Trough-like Formation (Syncline) at West Castleton, Vermont. 

Splendid Specimen of Ribboned Slate from Quarry near Hatch Hill, N. Y. 

Remarkable Formation of Black Slate taken from Brownville, Me., Quarry. 

Slate Alternating With Bands of Uncleft Rock at Rupert, Vt., . 

Shale Resting on Valuable Bed of Slate, Fairhaven, Vt., . 

Alternating Beds of Slate and Fissile Sandstone, Brownville, Me., . 

Single Saw Table, Proctor Quarry, Peach Bottom Ridge. 

The William Quigley Homestead, near Delta, Pa., showing Peach Bottom Slate Roof. 

Dressing, Splitting and Pillaring in the Dinorwic Quarry, North Wales, . 

Ground Plan of the Ideal Slate Quarry, .. 

Movable Crane, Slate Bucket and Storage Yard in Ideal Quarry, . 

Plan of Roofing Slate Department, . 

Ground Plan, Structural Slate Building, Proctor Quarry, . 


Page 
11 
15 
19 
19 

23 

27 

3 1 
33 
37 


4 i 


45 

49 

49 

5 i 

5 i 

55 

59 

59 

65 

65 

69 

72 

75 

79 

87 

89 

9 i 

93 


The 

Story 

of 

Slate 





























/ 




FOREWORD 


T HE story of slate has been written before, but always with a wealth of scientific terms and 
technical description which renders it impossible for the ordinary intellect to grasp. The 
writer claims no originality beyond his endeavor to describe the history, geology and chem¬ 
istry of slate in language the average man can understand. The sources from which the 
information contained herein have been gathered are: the reports of the United States Geological Sur¬ 
vey, Department of the Interior; by Prof. T. Nelson Dale, F. C. Eckel, W. F. Hillebrand, A. T. 
Coons and others; from the Encyclopaedia Brittanica and from personal observation and research. 

The ages at which the earliest formation of slate are said to have begun are described respectively 
as Upper and Lower Silurian, Cambrian, Devonian, etc., The standard dictionaries define these ages as 
the Paleoloic period of the earth’s formation, which in itself scarcely accomplishes more than add to 
the mystery. Further research tells us that the Paleoloic period was when coral formations began and 
invertebrae (without spine or backbone) were the denizens of the deep. The writer has classed 
these several ages as prehistoric, which is sufficiently simple for the ordinary person to comprehend. 
Many slates have an odor, which is described as ‘'argillaceous.” This means simply that the smell of 
clay is present in them. Good slates have a “semivitreous” ring, which in plain English means that 
when the slate is tapped gently with a hard substance, the sound is similar to that produced by striking 
a piece of china or thick glass. “Fissility” is another academic term which signifies capable of being- 
separated into thin layers or leaves, while “cleavage’’ means the general direction in which the blocks 
of slate will split naturally. 


The 

Story 

of 

Slate 


While these technical words define precisely the several factors of slate, the simple words em¬ 
ployed here will not always convey the exact shade of meaning, but rather the general sense, the 


9 






The 

Story 

of 

Slate 


former being sacrificed to a degree in order that the meaning may be clearer to those whose educa¬ 
tion is not technical. The chemistry of slate has been largely omitted for the same reason. 

The object of this little book is not to decry any slate on the market nor to unduly laud or praise 
the slate from any particular part of the globe, but to show the difference between the best roofing slate 
in the world and others of inferior quality. 

Only the expert on slate as a rule, knows that any difference in quality exists. Yet it must be 
borne in mind that even the poorest quality is better and more lasting than any artificial roof can 
possibly be. 

If the writer has succeeded in making clear some of the knotty problems, the object of his labor 
has been accomplished, and the public can understand something more of this great industry than 
can be learned from others works designed solely for the scientist and those learned in prehistoric 
lore. There may be errors due to the difficulty of simplifying the many academic words, but the work 
at least has been conscientiously done. 


]0 



The 

Story 

of 

Slate 


Part of the old Proctor quarry on Peach Bottom ridge, from which were quarried the first slates 
ever taken out in this country. The Proctor quarry was opened by Thomas Proctor in 1802, and fur¬ 
nished the dark blue-gray slate that was awarded the first prize at the Crystal Palace Exposition, Lon¬ 
don, Eng., in 1850, as the “BEST SLATE IN THE WORLD.” 










The 

Story 

of 

Slate 






THE STORY OF SLATE 

I N the ages past, primitive man was not interested in the history of slate and was supremely sat¬ 
isfied with the knowledge that it protected him from the inclemency of the weather. But the 
scientist arrived with a more mature civilization. He began to delve into the structural, min- 
eralogical and chemical features of roofing slate. These factors are now well understood. 
Sedgwick, Sorby, Phillips, Tyndall, Daubree, Gosselet, Jannetaz and Becker are names associated 
closely with this research and complete analyses of the varied slates have been given to the world. 
These published treatises, however,, are all academic works and the descriptive words used are such 
that the ordinary man is bewildered with the technical terms. Shorn of this scientific description, 
roofing slate of the better class is by far the best and most serviceable protective roof that has ever 
been discovered since the world was young. 

Papers of academic or technical nature have been published from time to time upon the slate pro¬ 
duction in America. Their circulation, however, has been limited to the few persons and societies 
scientifically interested in them and no effort has really been made to place the simple facts of this 
important branch of American industry before the general public. 

There is, perhaps, no other line of business about which so little is known by persons aside from 
those financially or scientifically interested in it. That slate is simply slate, seems to be the impression 
of the average buyer. His information is limited to the one fact that slate does make a good roof, 
but he takes little or no account of the various grades of slates. Pie sometimes knows by experience 
that some slates are good, while others fade and discolor quickly, and break after a short period ctf 
exposure; but he probably does not know why they do so, and he has yet to learn how to distinguish 
the good and avoid the bad slate. 

Slate is a rock of various colors formed from prehistoric clay—blue, purple, green, gray, black 

• T 2 


m 



or red—and of a peculiar texture by which it is easily split into thin plates or layers. Those who The 
have studied its origin agree that it was originally a sediment or mud on the floors or bed of the Story 
ocean when the earth was without form and its surface was a waste of tumbling waters. This mud Q f 
had been s>wept by the action of the waves from rocks and was afterwards compressed and hardened Slate 
as the ages rolled by. It is an accepted fact that slate beds occur in about the same period of the 
earth’s evolution as when coral reefs began to form. 

These rocks, having been tilted from the original horizontal positions, probably through volcanic 
action, stretch across broad districts which arose to the earth’s surface in crests and formed planes 
that to-day exist almost at right angles with their original horizontal positions. The result of the pow¬ 
erful forces that have accomplished this marvelous work are seen in the wavy contortions of the slate 
rock. 

The relative commercial value of several slates is an index of their characteristics. Mathews, 
an acknowledged authority, has given these prices for slates 14 by 7 inches, three-sixteenths thick, 
per square (which means capable of covering 100 square feet of roof) : PEACH BOTTOM, $4.85; 
Northampton County, Pa., $3.50; Lehigh County, Pa., $340-$3.95; Arvonia, Va., $3.60; unfading 
green, Vermont, $4.50. 

The following prices per square for slates of the best quality, 16 by 8 inches, f. o. b., were 
obtained by Dr. Day from producers: PEACH BOTTOM, $6.35; Bangor, Pa., $5.75; Albion, Pa., $5 ; 

Pen Argyl, Pa., $4.75; Chapman, Pa., hard vein, $5.25; Slatington, Pa., $4.50 to $5; unfading 
green, Vermont, $4.50 to $5.25; sea green, Vermont, $3.50, Virginia, $5 to $5.50. 

To-day although slate is a comparatively new factor in the commerce of the United States, the 
splendid quality of Peach Bottom slate has attracted attention throughout the civilized world. 

This noted slate deposit derived its name from that of a small village a quarter of a mile west of 
the Susquehanna river and was formerly a port on the now disused canal which follows the stream. 


13 


The It is situated in York County, Pennsylvania, and extends to the Maryland line. The United States 
Story ( Geological Survey report, under the head of Slate Deposits and Slate Industry of the United States, 
of compiled by T. Nelson Dale, goes thoroughly into the subject of Peach Bottom slate. He says in 
Slate part: “Peach Bottom slate is a very dark gray, with a slightly bluish tinge. To the unaided eye its 
texture is minutely granular, crystalline with a lustrous surface and it does not discolor. The highly 
crystalline or glass-like character of the matrix and absence of carbonate indicate a very durable 
slate.” 


There are eleven quarries on the Peach Bottom ridge, of which, namely the Pennsylvania-Mary- 
land, thirty-three acres, and the Proctor, (45) acres, the Henry twenty-three acres, together with a one- 
fourth interest in the (50) acre tract lying south of the Proctor properties and the (298) acre farm 
of the late Edward P. Stubbs, are under the direct control of J. G. Feist & Company, Banker's of 
Harrisburg, Pa., and their associates. 


These are doubtless the most important of the slate quarries in the United States, 
other side of the Atlantic arc also of great importance from an industrial viewpoint. 


Those on the 


The Delabole quarries of Cornwall had acquired a goodly amount of importance as far back as 
the 16th century, while some of the old Welsh quarries date even further back into the dim past. But 
the slate industry, as a commercial factor belongs to the present time. 

Among the largest and most valuable of the Welsh quarries are those of Llanberis, Penrhyn, 
Festinog and Dinorwic. There are also quarries in Cumberland, Westmoreland and Lancashire, the 
lake districts being especially noted for their rich green slates. Some of the western and midland dis¬ 
tricts of Scotland, mainly Argylshire, Dunbartonshire and Perthshire produce strong and durable 
slates, the largest quarry in the land of the Heather being at Ballachulish in Argylshire. The Scotch 


14 



Old Peach Bottom Mill, whose rough stone walls have borne the same roof of Peach Bottom slate for 
1 ‘50 years The roof to-day is the same deep blue-gray color, and is as perfect after nearly a century 
and a half of exposure, as when it was laid atop the rafters, which, by the way, have been replaced 
more than once. The creaking old wheel has been stilled many years. 


The 

Story 

of 

Slate 















The slates are chiefly blue in color, although thin beds of green slate arc found in some of the districts. 
Story Good slates are also found in the south of Ireland particularly in the counties, Wicklow, Tipperary, 
of Cork and Kerry, while on the continent of Europe slate is quarried in France, Belgium, v Sweden, 
Slate Norway, Germany, Austria and Italy. 



METHODS OF TESTING SLATE 

ETHODS of testing the elasticity, absorption, fissility, and resistance of roofing slates have 
been in use for many years, and a number of more or less complete chemical analyses of 
slate have been published. In recent years, however, more exact methods of reaching 
these results have been devised. The best of these methods have here been brought 
together and several of them are of so simple a character as to be easily applied. This list of tests is 
largely compiled from Bottinger, Fresenius, Hutchins, Jannetaz, Merriam, Reverdin and de la ITarpe, 
Sorby, Umlauft, and J. F. Williams. All offer valuable suggestions. 

Sonorousness, or ringing musical sound —One of the first and most time-honored tests of roofing- 
slate is to suspend a good-sized piece of the usual thinness and tap it with some hard object. If it 
possess the structure of a slate it will yield a clear, musical, ringing sound. A clay slate will be less 
sonorous or ringing than a mica slate, but mica slates with a large percentage of chlorite and possibly 
little talc will be deficient in sonorousness. It is because of this property that at the quarries 


a 


The 

Story 

of 

Slate 


when refuse slates are thrown upon the dumps, the sound produced is not unlike that made by the 
smashing of a large quantity of crockery. 

Cleavability, or the property of splitting smoothly and evenly —This test should be applied by an 
experienced workman. The block should be freshly quarried, unfrozen and moist. The chisel should 
be thin and about two inches wide. The cost of slate is closely related to the degree of its cleavability. 

Cross fracture, or the property of splitting along the grain across the cleavage—(In the Penn- 
sylvania-Maryland and Proctor Peach Bottom quarries, the electrically-driven saws largely take the place 
of the heavy chisel and mallet.) This is to determine the character of the "grain." This test should 
also be applied by an experienced hand to a large block several inches thick, with a stout chisel and a 
long-handled heavy mallet. Jannetaz has published a method for determining exactly the direction 


1 7 


The of the grain in slate when it is but obscurely shown on the cleavage surface. The slate is sawn in a 
Story direction parallel to its cleavage and one of the sawn surfaces is made exceedingly smooth and cov- 
of ered with an even and very thin coat of grease. The point of a red-hot platinum wire is applied to the 

Slate slate opposite the centre of the greased surface. The greased area reached by the heat will, in cooling, 

leave an oval outline, the greatest length of which will show the direction of the grain, the heat hav¬ 
ing traveled more rapidly within the slate in the direction of the grain than in any other. He also 
made a disc of slate live inches in diameter, of ordinary thickness, with a central perforation or hole. 
This disc was fastened by the extremities of the diameter parallel to the grain and afterwards by 
that at right angles to the grain, and was made to vibrate by tapping the side of the perforation. 

The sound produced when the disc was fastened by the diameter at right angles to the grain was 

louder than when fastened by that parallel to it. In other words, the direction of the grain was that 

in which elasticity and vibration were greatest. 


Character of cleavage surface —The cleavage surface should be examined with an ordinary magni¬ 
fying glass. A superior slate should scale along the cleavage surface into very thin chips with trans¬ 
lucent (almost glasslike) edges. If the grain is pronounced it will appear in fine lines. Ribbons, 
which are sometimes lines of weakness, should be noted. There is great difference in the smoothness 
of the surface in slates of different regions and smoothness is a desirable quality. 


Color and discoloration —The color of the freshly-quarried slate should be noted and compared 
with that of pieces exposed for several years to the weather, either on a roof or on the quarry dumps, 
or with that at the top of the quarry close to the gravel, although this last comparison may not always 
be entirely conclusive. The value of the slates is affected by the extent of their discoloration, as it 
means the presence of some matter causing change, and naturally decay. 

Presence of clay —This should be tested by breathing upon a fresh and clean piece of slate and 

18 



Trimming slate in the old way at the Proctor 
quarry at Cardiff, Maryland. This slow process 
has been the vogue for many years. The foot 
power knife has not yet reached Europe. 



The 

Story 

of 

Slate 


The splitters at work on Peach Bottom ridge. 
There is something humanly necessary in this slic¬ 
ing great blocks of slate into thin layers or leaves. 
No machinery has as yet been devised for this work. 









The 

Story 

of 

Slate 


observing whether .there is any odor of earth or clay. The very best slate, such as Peach Bottom, 
will not emit any such odor. 

Presence of marcasite -—A slate containing crystals of a pale-yellow metallic mineral which, on ex¬ 
posure, decomposes, forming a yellow white film and rusty spots, is poor. 

Strength —Merrianrs method for testing the strength of slate is here described. 

The pieces are supported in a horizontal position upon wooden knife-edges twenty-two inches 
apart, and these loads are placed upon another knife-edge halfway between the supports. The load 
is applied by means of sand running out of an orifice or hole in a box, at the uniform rate of seventy 
pounds per minute, and by the help of an electric attachment the flow is stopped at the instant the slate 
breaks. According to these tests, the measure of elasticity before the slate breaks in the best slates 
should range from 7,000 to 10,000 pounds. This is computed on the total weight borne by the slate 
reduced to the pressure per inch. Peach Bottom is about eight times as strong as any other Penn¬ 
sylvania slate. 

Merriam has also devised an impact test for determining the strength of slates. He lets a wooden 
ball weighing 15.7 ounces fall nine inches upon a piece of slate measuring six by seven and three- 
quarters inches by from 0.20 to 0.28 inches thick, and repeats the blows until the slate breaks. The 
foot pounds of work per pound of slate are then calculated from the weight and thickness of the 
slate and the number of blows. 

Elasticity —Merriam finds certain Pennsylvania slates, when placed on supports twenty-two inches 
apart will bend from 0.270 to 0.313 inch before breaking. Certain blue-black slates in Eldorado 
County, Cal., when split seven to the inch and eighteen inches square and fastened solidly at the two 
ends are said to bend three inches in the centre without any sign of breaking. 

Density or specific gravity —This is determined by weighing a piece of the slate in and out of 


20 


water and dividing its weight out by the difference between its weight in and out. All air should first 
be removed by boiling the piece of slate in distilled water. 

Porosity (water-proof quality )—This is best determined by drying and weighing, then immersing 
for twenty-four hours and weighing again, in order to ascertain the percentage of water absorbed. 
Merriman takes a piece three by four inches, will rough edges, dries it in an oven at 135 F. for 
twenty-four hours, cools to the normal temperature of room, weighs, and immerses it for twenty-four 
hours, and weighs again. His tests of Pennsylvania slates showed from 0.099 to 0.303 per cent, of 
absorption. Porosity is sometimes roughly estimated by immersing a roofing slate edgewise one-half 
in water and observing how far the water ascends on the dry part of the slate. In good slates it should 
rise but very little. 

Hardness, or abrasion —Merriman has also devised a method of testing the relative hardness of 
slates by subjecting a piece of known weight to the action of a grindstone revolved 50 times, the 
slate being held against it by a lever, with a constant pressure of ten pounds. The loss of weight 
in the process is then determined. 

Corrodibility —An important quality in roofing slates is their resistance to the acids of the atmos¬ 
phere, particularly in cities, where gases increase their destructive power. Fresenius suggested testing 
the weathering qualities of a slate by immersing it for three days in dilute sulphurous acid in a closed 
vessel. At the end of that time poor slates are softened, broken up or easily fractured, while good 
ones preserve both their density and hardness. 

In conclusion it must be remembered that the strongest and best slate stands highest in weathering 
and non-corrosive qualities. Chemical analyses give only imperfect results regarding these qualities, 
for from the view-point of the scientist, slate is a complex rock. The best test is that of time, such as 
is shown on the old Peach Bottom mill, where the slate roof has stood the test for more than 130 years 
and is still in excellent condition. The old Presbyterian Church at Peach Bottom, has been sur- 


The 

Story 

of 

Slate 


21 





The mounted by the same Peach Bottom slate roof for a century and the same slates had already been 
Story used on several other structures which had decayed before they were placed on the house of worship, 
of The foregoing tests are the principal ones used for the purpose of distinguishing good slates 

Slate from those of inferior quality. There are still other tests for learning the degree of corrosion as in¬ 
fluenced by the gases of a city, a railroad, etc.; and for the effect of heat and cold on slate. These 
tests are elaborate and complex and are unsatisfactory to the layman. Therefore they are omitted in 
this work. 



22 



The 

vStory 

of 

Slate 


Galleries showing great Slate Quarry at Port Dinorwic, North Wales, which has been worked for 
two hundred and fifty years, but only during the last century lias the slate been quarried systematically. 
The galleries are each 75 feet high and 3,000 persons are employed in the quarry. 






The 

Story 

of 

Slate 


A NOTABLE WELSH QUARRY 

P ROBABLY the most important quarry in North Wales is the Dinorwic, which has been a fertile 
field of profit for more than two hundred and fifty years. This quarry is on the north flank 
of Mount Snowdon in the Llanberis pass. True, work in a systematic manner has been 
prosecuted only for about 150 years, during which period the quality, durability and strength 
of its slates have been heralded around the world. Indeed, until the Peach Bottom product reached 
England and won the first premium in the Crystal Palace Exposition as the “best slate in the world” 
the Dinorwic or Velinheli slates were considered superior to any others, and the name of the little 
Welsh seaport, whence they are shipped to London and from there to all quarters of the earth, be¬ 
came famous. Port Dinorwic on the Menai Straits, would be unknown but for the enormous slate 
industry carried on about six miles inland. 

As shown in the accompanying engraving, the Dinorwic quarry consists of a series of galleries 
or terraces cut one above the other into the face of the Elidir mountain, receding like a giant’s stair¬ 
case from the floor of the quarry (which in places is below the water of Lake Padarn) to the top of 
the mountain. From the lowest gallery to the topmost the height is 1,800 feet, each terrace seventy- 
five feet in height. Viewed from a convenient eminence, one sees the great galleries rising one upon 
another in tiers to the very shoulder of the mountain. An interesting fact is that men are working 
in the same galleries to-day in which their fathers and grandfathers worked the same strata from 
thirty to sixty years ago. 

And this stupendous work, this slicing away of a great mountain in shreds less than a quarter of 
an inch in thickness, has been progressing for centuries without improvement in methods. It is true, 
dynamite is used to loosen the slate, but the sledge, the crowbar, the dresser’s knife, the splitter’s chisel 
and hammer are the primitive tools with which this big hill is being taken piecemeal from the face of 


24 


the earth. The single improvement is a system of narrow gauge railway which facilitates the removal The 
of debris and the carrying of the huge blocks to the 
is also a railway for carrying the finished slate down 

On the continent and in the United States, the same primitive methods have also obtained until gfate 
the advent into the Peach Bottom section of J. G. Feist & Company of Harrisburg, Pa., whose con¬ 
sulting engineer, George J. Atkins, at once discarded the time-worn methods which have been in vogue 
since the days of the crusaders, and introduced twentieth century machinery on Peach Bottom Ridge. 

Of the quarries in the vicinity of Delta, Penna., which is the centre of the Peach Bottom slate in¬ 
dustry, the Pennsylvania-Maryland quarry was first equipped, and the hand of the Yankee necro¬ 
mancer who accomplishes things is shown both by the increased output of the quarry, and by the 

* 

reduction in cost for bringing the slate from its original bed to the railroad. 

There are other quarries on the ridge, but in them the ancient methods still prevail. The 
Pennsylvania-Maryland and the Proctor quarries alone are equipped with up-to-the-minute machinery. 

In everything, from hoisting the great quarried blocks, carrying them across the mouth of the pit on 
taut wires to tables, above which move multiple saws, electricity plays its part. Only the splitting is 
done by hand and the factor of waste is practically eliminated. In detail, the blocks of slate are car¬ 
ried from the bottom of the quarry and swung on a moving platform which brings the rough block 
to a table directly under a series of six saws, set at equal distances from each other and which quickly 
cut lengthwise through the block. Automatically the saws whirl backwards, the table moves forward 
to a point where six similar saws sweep transversely through the blocks and return to their station. 

The blocks are now the required size and the table delivers them to the splitters who speedily 
cleave them to the required thickness. As each individual slate is separated from the block it is placed 
on a moving tramway or conveying belt and carried to the storage yard, where boys stack them up 
in squares ready for shipment. The new machinery, in addition to delivering perfectly cut blocks to 


sheds where they are split and trimmed. There Story 
to Port Dinorwic for shipment. Q f 


25 




The the splitter, eliminates the trimmer and very largely the factor of waste, as the entire block as it is 
Story taken from the quarry, except the rough and uneven edges, can he utilized for roofing slate. Instead 
of of a loss of between seventy and eighty per cent, of the slate quarried, as under the old regime, scarcely 

Slate ten P er cen t. reaches the scrap heap and this, too, is now used for scores of useful purposes. 

Peach Bottom slate is invariably called for by the United States Government for roofs of all 
public buildings and where possible to obtain it, has been insisted upon by reason of its unchangeable 
color, elasticity and wearing qualities. The Pennsylvania and Baltimore and Ohio railroads also in¬ 
sist on Peach Bottom for similar reasons. When it is recalled that corrosive gases are more in evi¬ 
dence in the vicinity of railroad shops, roundhouses, etc., one can easily understand why none but the 

best roofing- material can last for any long period without corrosion. The Peach Bottom district is 

comparatively small in area and the slates quarried there are of the general division called “mica” 

slates. 



26 



General view of the Diliorwic Slate Quarry, in Llanberis Pass, North Wales, showing Pekis Lake in 
the foreground, and Mount Snowden in the distance. This picture shows the galleries and approaches 
to the most important slate quarry in Europe, from which the best slates in the world have been taken 
until Peach Bottom Slate was discovered. 


The 

Story 

of 

Slate 





The 

Story 

of 

Slate 


QUARRYING SLATES IN FRANCE 


T HE methods employed in working the slate deposits of France are as follows: The strata 
of fissile rock capable of being split into roofing slates are almost vertical, and it is 
vertically also that the work of quarrying them is pursued. There are two methods of 
mining the slate rock. The first of these is the open air method, in which, after the re¬ 
moval of the top bed , the slate, cut into easily handled blocks, is raised to the surface. In the second 
method, a shaft is sunk, in order to reach a slate of good quality, and then a chamber is excavated 
from which the blocks are raised to the surface in order to be split. Above the chamber there is 
left a certain thickness of slaty rock, which possesses great solidity, and the layers of which become 
as it were, long girders which 'form part of the side walls at their extreme ends. Under this vault, the 
excavation descends, while the blocks of slate are raised in a bucket which slides over cable stretched 
above the heads of the workmen. But since the roof of the vault, however carefully it may have been 
chiseled out at first, becomes weak in the long run, and since it is impossible to easily inspect it after 
the chamber has reached a great depth, blocks of stone have been known to fall with serious results. 
And, moreover, if inspection of the vault roof reveals displacements and fissures, the method of the 
miner is to desert the chamber, which will then become unworkable because of these cracks and threat¬ 
ened cave-ins. Such cave-ins have often extended to the surface and ruined the entire work as well 
as destroyed the hoisting machines installed upon the surface. 

In the method of quarrying recently introduced, which it is believed is destined to completely rev¬ 
olutionize the industry in France, the work is performed in chambers, as before, but from the bottom 
upward. In the former method, it is the floor from which the slate is taken, while now it is the 
roof of the chamber that is worked. Successive layers of slate are cut from this by the workmen, who 
stand upon a platform suspended from the roof a part of which has been cut away. The slate, as 

28 


fast as it is quarried, is removed through horizontal galleries to the main vertical shaft, where it is 
immediately hoisted to the surface. The height of the chamber is kept always the same by building 
up the floor with waste material as fast as the roof is chiseled away. Thus, the waste material re¬ 
places the strata of rock as fast as they are removed from the ceiling, and the side walls have no 
tendency to fall in, on account of the extremely reduced height, which is by this method of working, 
kept always about the same. 

A beginning is made by sinking a shaft to a depth of from 500 to 1,000 feet, outside of, but close 

to the wall of the vein that forms the plane of contact of the slate deposit—a chamber is opened at 

each working point and pushed toward the other side of the vein. Its width is at right angles with the 
cross-gallery that connects with the main gallery, and its length is a prolongation of it. In this way 
there is established a working chamber from six and a half to thirteen feet in height, according to the 
more or less resistant nature of the hard rock. The excavating naturally is done in horizontal lines. It 
it sometimes necessary to raise the waste material to the surface, whence it may afterwards be let down 
again for filling in; but the order observed in the work generally permits of its being emptied immedi¬ 
ately into the chambers, the excavation of which is sufficiently advanced to allow the lower part to 
be filled in, in order that a stratum above may be taken out. The work is carried on therefore by 
cutting out the slate and afterward completely filling in the chamber thus made. In order to detach 
a block from the ceiling, workmen standing upon a footbridge or scaffolding hung from the roof of 
the chamber, cut in the entire length of the latter a cavity six feet in width by thirteen in height. This 
cavity is generally formed outside of the vein, and at its edge, starting from the working points, so 

as not to break the slate uselessly. It is then possible to drill blast-holes. A block of slate the entire 

width of the chamber is blasted out and falls upon the floor provided by the first work. The blocks, 
which are sometimes split into still smaller pieces are moved to the main vertical shaft and drawn 
to the surface. 


The 

Story 

of 

Slate 


29 



The After the first stratum or layer has been removed, work is begun on the second, and, after 

Story it is slightly advanced, there is excavated, outside of the vein, a new gallery which will end at the 
of new ceiling, at a height of twenty-six feet above the original floor, and which is connected with the 

Slate main shaft parallel to the vein. In this way, by means of this new system o'f galleries, it is pos¬ 
sible to remove slate to the surface at the same time the waste material is being thrown into the 
bottom of the chamber in order to raise the floor by the thickness of one stratum. The waste ma¬ 
terial is distributed through the upper galleries, while the slate and rock that falls from the ceiling is 

shoveled into cars and carried through the lower galleries, the entire length of which is protected 

by timbering. 

The quarrying (or more properly, mining) continues thus until, in ascending, the useless stratum 
of rock is reached. Moreover, when it is desired to work a vein of great thickness, it is preferred 

to divide the field of operation into two parts, by sinking the shaft toward the centre of the vein 

and opening chambers on each side. 

Electric light has been adopted in many of the slate mines of the Angers region, and in addition, 
the Societe des Ardoisieres o'f Anjou, the inventor of this method of mining, has constructed and is 
regularly employing, for moving the blocks in the chambers, and loading them upon the cars, electric 
windlasses which a boy can operate and which have all the power desirable, while affording absolute 
security against accidental descents of the load. 


30 



Portion of Quay 
loaded on L. & N. W. 
six miles inland from 


at Port Dinorwie, 
Railway's main line 
which the Dinorwie 


Xortli Wales, showing slates from Dinorwie Quarries to he 
for transit. Port Dinorwie takes its name from the quarry, 
or Velinheli Slates are taken. 







The 

Story 

of 

Slate 


PEACH BOTTOM SLATES 


T HE village of Peach Bottom is in a triangular township of the same name, which is bounded 
by the Maryland line on the south, the river on the northeast, and in part by Muddy Creek 
on the northwest, and which forms the southeast corner of York County, Pa. The slate 
forms a belt and low ridge from one-fifth to one-half mile wide, which extends from a point 
about a mile northeast of the Susquehanna, imthe town of Fulton, in Lancaster County, Pa., across the 
river and across Peach Bottom township in York County, and continues for about three miles in the 
same direction into the town of Cardiff, in Harford County, Md. Its total length is about ten miles, 
of which one mile lies in Lancaster County, Pa., one and one-half miles are submerged by the Sus¬ 
quehanna, four and one-half are in York County, Pa., and about three miles are in Harford County, 
Md. Most of the quarry population is congregated along one street, which follows the western foot 
of the ridge. The northeastern part of this street is Delta, Pa.; the southwestern is Cardiff, Md. 

The slate belt has on its northwestern side a deposit of slate, lustrous and silky, resembling mica, 
in which at varied distances are imbedded hard semi-transparent stones similar to quartz. About 
midway between Delta and Bryansville this slate becomes harder through the fact that these flinty 
crystals become more frequent. According to the reports of the Second Pennsylvania Survey, similar 
fields of slaty substance recur on the southeastern side of the slate belt, and the whole formation leans 
or inclines toward nearby formations of grain-like surfaces, which occur on either side of it. There is 
a good exposure of slate on the east side of Slate Point, on the towpath along the Susquehanna. The 
slate here underlies about fifty feet of quartz (a hard flinty stone) which was formerly quarried for 
canal construction. A little farther east this is 'followed by deposits of coarse granite-like rock. This 
rock apparently continues into Lancaster County, for in looking across the Susquehanna from Slate 
Point, a considerable thickness of light-colored rock can be seen overlying the slates there. 


32 



A corner of the rich Pennsylvania-Maryland quarry on Peach Bottom ridge, showing the almost 
vertical slate formation that is the rule at Delta, Pa., where this profitable quarry is situated. The 
deep blue-gray slate from this quarry is greatly sought by architects and contractors who desire tbe 
unfading- mica slates from Peach Bottom ridge. 


The 

Story 

of 

Slate 








The 

Story 

of 

Slate 


The Delta and Cardiff quarries lie in three parallel lines and range from 75 to 120 feet across and 
up to 200 feet or more in depth, all of commercial roofing slate. The cleavage is uniformly vertical or 
nearly so, and there is usually a “big fat joint" sometimes from forty to sixty feet from the surface and 
including two to three feet of crushed slate, which is evidently the result of a secondary volcanic move¬ 
ment of the earth's surface. Commercial slate occurs below this joint. The “top" varies from forty 
to sixty-five feet and in places includes ten feet of slate in small fragments. The slate usually has 
along the planes toward the surface, a brown rim, called a “hem," from one to two inches wide. These 
hems represent simply the initial stage of weathering caused by the dripping and seeping through of 
water from the joints, of which process the final result is the red clay. The slate of the top has gen¬ 
erally a red hue, and the whole belt is covered with red clay. 

The slate districts of America are divided into two distinct classes which are known by the period 
of their formation as the Cambrian and Silurian, the meanings of which are defined in the. foreword. 
The Cambrian deposits, from which the Peach Bottom are taken, are lower and older than the Silurian, 
from which are produced inferior slates. 

As in all other lines of business there is some one make of goods which ranks higher in quality 
than all others in its line, so it is with the various kinds of slate, among which the genuine Peach Bot¬ 
tom ranks not only higher than any other American slate, but is regarded, by many prominent 
architects and builders, as the best slate in the world. This assertion is made because it is known to 
be a fact and authorities agree that such is the case. 


'The most satisfactory evidence regarding slate is the number of years of actual use. Such a test 
proves the most important fact about it, i. e., its durability. The genuine Peach Bottom slate has 
stood the test of 165 years constant, actual use ; the first pieces made in 1734 being still in evidence 
and doing good service to-day. This is a test of nearly 100 years longer than to which any other 
American slate has been put and is the first reason for the assertion made of its being the best slate 


34 


in the world. Tn chemical analysis it far out-ranks other makes. In color (dark blue gray) it sur¬ 
passes all others for it is positively unfading, and grows darker with age. It has none of the disfigure¬ 
ments that are characteristic of inferior slates, i. e., ribbons, and finally, it was awarded the highest 
premium over other slates by the London Crystal Palace Exhibition in 1850, as being the best slate in 
the world. 

At the time of the Crystal Palace exposition, the Proctor quarry was in its infancy, while the 
Penrhyn and other quarries in North Wales had at that time been worked commercially for more than 
a century. Records show that slate was quarried in Wales a century before the first crusade and as 
far as authentic records exist, it was in that country that the desirability and usefulness of roofing 
slate was first discovered. It is said that some of the old Welsh castles—such as Carnarvon and Con¬ 
way—were covered with this material. No doubt the better class of houses, situated in the neighbor¬ 
hood of slate beds were covered with slates obtained by rough surface digging or from blocks exposed 
by mountain streams and split by the action of the weather, long before the man of the stone age 
learned that slate could be sliced through the introduction of a wedge forced by the tap of a large 
stone. To-day the same method of splitting the slate exists, with the exception that a steel chisel and 
wooden mallet are substituted for the wedge of flint and the stone hammer. 

Previous publications have instanced the roofing of the old Slate Ridge Presbyterian Church, near 
Delta, Pa., in 1805, with Peach Bottom slate, as being the first use of slate in America, while, ,as a 
matter of fact this slate had then been in constant use for seventy years on another building before it 
was placed on the House of Worship. The quarry from which the slate for this church was taken 
was owned by Thomas Proctor and opened by him commercially in a small way, at Cardiff, Md., in 
1802. It is the same quarry owned and operated by the Proctor Slate Corporation to-day. 

The early history of the use of slate in America is as follows: “Two brothers, William and James 
Reese, natives of Wales, took up land in 1725 under patent of the English Provincial Government, 


The 

Story 

of 

Slate 


35 


The 

Story 

of 

Slate 


in what is known as York County, l’a., and during the year 1734, when excavating for foundations 
for farm buildings, they discovered the slate rock from which they split the pieces necessary for roofing 
their out houses. This was the first use of slate in America (1734).” Those pieces are still in use, 
upon the property now belonging to Capt. David Jones, near Delta, Pa., and covering the seventh 
building upon which they have been placed. They show no disintegration or decay and still retain 
the strong, brilliant blue-black color for which this slate has become famous by the name of Peach 
Bottom. Numerous other instances are known of persons in this county following the example of 
the Reese brothers in using this slate for roofing purposes, during the years succeeding 1734, but it 
was not until 1785 that any effort was made to produce slate as a marketable commodity in America, 
when, during that year (1785) the first slate quarry for the sale of slate was opened by William 
Docker, in Peach Bottom Township, York County, Pa., and from that time dates the production of 
slate commercially; the name of the township (Peach Bottom) was then given to the slate. 

The production of this slate steadily continued until 1846, when several operators of the slate 
quarries in Wales came to this region. With this added impetus the business became greatly broadened 
and increased. Among the newcomers was Capt. David Jones, who still resides upon his farm near 
Delta, Pa. Close to his residence, and on his farm is the place where the first slate'used in America 
was discovered by the Reese brothers and the first quarry opened by William Docker. Mr. Roland 
Parry came to this region in 1847 a °d quarried this slate for several years returning to Wales about 
1857. During the Crystal Palace Exhibition in London in 1850, Mr. Parry exhibited samples of Peach 
Bottom in competition with slate of other countries: ‘‘THE PEACH BOTTOM SLATE WAS 
AWARDED THE HIGHEST PREMIUM OVER ALL OTHERS AS BEING THE " BEST 
SLATE IN THE WORLD.” 

The producers of Peach Bottom slate have always conducted their business in a quiet, conservative 
manner. Very little money has ever been expended in advertising, as they preferred their slate 


36 



The 

Story 

of 

Slate 


This ravine on Peach Bottom ridge at the Pennsylvania-Maryland line, gives an idea of the si yr 
of slate blocks that are being quarried on the ridge. These larger blocks are best adapted for struc¬ 
tural purposes. The fresh slates split to far better advantage where they have not been exposed to 
the weather for more than forty-eight hours. 







I 


The 

Story 

of 

Slate 


should retain its high reputation through its own merits, rather than by self-praise through news¬ 
paper and other advertising mediums. This course was satisfactory until the introduction of imita¬ 
tions of their slate. It is because of its high merits that Peach Bottom is the only slate which is 
imitated and the imitation consists in simply naming and selling other slates as being Peach Bottom 
slate. 

The imitations arc known as the “Slatington Peach Bottom," “New Peach Bottom," “Lehigh 
Valley Peach Bottom,” and “Peach Bottom of Lehigh Valley." The assumption of the name “Peach 
Bottom" is apparently for the purpose of deception. Instances are known of these imitations having 
been sold and substituted where the Peach Bottom was specified and desired. The careful contractor is 
not now easily misled by the imitations. Some of the producers of these imitations have made the mis¬ 
leading statement that their Peach Bottom slates were produced from one end of the same ridge from 
which the genuine Peach Bottom is taken; which is entirely false. The ridge from which the genuine 
Peach Bottom slate is taken, is situated in York County, Pa., and Harford Countv, Md., extending 
about three or four miles on either side of the Pennsylvania-Maryland line; the ridge from which the 
imitations are taken is nearly one hundred miles distant. 

In its sales history, Peach Bottom slate is recorded as being used upon the highest class of 
buildings, a short list of which is appended. The United States Government has for a number of years 
recognized the high standard of the genuine Peach Bottom slate and the several Government Depart¬ 
ments specify it when requiring slate for their buildings. 

Along with other makes of slate, this slate has been subjected to all manner of tests by prominent 
geologists and scientists, and in every case has it surpassed its competitors in strength, color, durability 
as well as in chemical analysis and compression tests. It is a remarkable commentary upon the dura¬ 
bility of Peach Bottom slate that all the old roofs of it still retain their remarkable color, and even the 
most experienced slater cannot tell from their appearance which is the oldest. 

38 


While it is true that the genuine Peach Bottom sells higher than other makes of slate, still, eco¬ 
nomically speaking, it is the cheapest slate on the market, for in it is combined all the highest quali¬ 
ties at a minimum of cost. The question of repairs, so important a factor in the use of inferior slates, 
does not need consideration when using Peach Bottom; THE FIRST COST WITH IT IS ALSO 
THE LAST COST 


By severe chemical tests for corrodibility, as well as by actual use, they have proven to be particu¬ 
larly serviceable upon such buildings as railroad shops, roundhouses, chemical laboratories, gas works, 
iron furnaces,' and any buildings where fumes of gases and chemical elements abound. In the slate 
storage yards the pieces are kept in ricks on what is known as slate banks. They are not housed or 
stored in sheds, like inferior slates, as they are not affected by any extreme of temperature or by the 
elements. 

Remarks from an article by Prof. Merriman, entitled “The Strength and Weathering Qualities of 
Roofing slates” read December 19th, 1894, and published by the American Society of Civil Engineers, 
includes the following: 

“In splitting and dressing the roofing slate, it is always done so that the grain runs parallel to 
the longer side of the rectangle. This grain, although never so marked as that in the timber, has a 
similar effect upon the strength in directions. The strength and weathering qualities of slate or stone 
depend, not merely upon its chemical properties, but on the manner in which the grains are cemented 
together. For the determination of this, microscopic inspection is necessary.” Peach Bottom slates 
have stood this severe test with excellent results. 

In a letter by Geo. P. Merrill, Esq., (Curator of Department of Geology, Smithsonian Institution, 
Washington, D. C.) upon the above article, this well known authority says: 

“Not to go too much into detail, it can be said, that in short, the clay slates pass by imperceptible 
gradations into crystalline (or glass-like) factors capable of being split into thin slices, and, further, 


The 

Story 

of 

Slate 


39 


The 

Story 

of 

Slate 


that so far as the writer’s present experience goes, the more crystalline the rock is, other thing's being 
equal, the stronger, less absorptive and more durable it is. This is well exemplified in the Peach Bottom 
slates referred to in Prof. Merriman’s paper. These are among the most highly crystallized of any 
of the cleavable slates that are used for roofing purposes. The microscope shows in them crystaliza- 
tions which tend to give them great strength and elasticity. In the few cases in which the writer has 
been called upon to decide as to slates for roofs of public buildings, his decisions invariably have been 
based upon amount of crystalization as shown by the microscope, and the presence or absence of sub¬ 
stances known to influence more or less rapid decay.” 

The value of Roofing Material is determined by a variety of considerations, amongst which the 
most important are, first cost, durability, appearance, resistance to fire and consequent influence on the 
cost of insurance, and the expense for maintenance or repairs. That there is a vast mass of false and 
misleading information prevalent on this point, even in the building trade, is evident, and in order to 
show at a glance what the actual facts are, we present the truth in a tabulated form, showing a com¬ 
parative estimate between the leading materials used in the Roofing Trade. 

The estimate is based on the square— too square feet of surface—laid on roof complete, in the 
vicinity of Philadelphia or New York. 


Material 

Peach Bottom Slate, 

J in, . 

Shingles, . 

Corrugated Tron, . . . 

Tin Shingles,. 

Copper, . .. 


First 

Average 

Av. Cost 

Cost. 

Life." 

per year. 

$7-5° 

150 years 

.05c 

5 • 50 

20 years 

.27.5c 

4-3« 

12 years 

.27.5c 

5.10 

10 years 

.57.2c 

6.70 

to years 

.67.2C 

30. (40 

40 years 

.75.00 


40 











- V * 






&r~ 




r^j 




i 




1 



Buff ‘ 'BBBWw 




mW&S- 





f 0 



SraysassR ■ 

' y 



nil i iimIm - ~m crlPinff 

HBtt ^y^*HQ)^MMnKvol 


The 

Story 

of 

Slate 


One of the picturesque hits of Cardiff, Md., is the “Owens Place,” the homestead of the Owens 
family for half a century. The Owens place is a type of house of which many were built during the 
days of the Civil War. To-day the plastered walls and chimneys show the work of the passing years, 
yet the ruthless hand of time has touched hut gently the Peach Bottom slate. 











































































































































































The 

Story 

of 

Slate 


Tt will be readily seen that a Teach Bottom Slate roof is not alone the most durable, hut when the 
original cost and average life are taken into consideration, it is five times cheaper than tin, seven times 
cheaper than shingles, eleven times cheaper than iron and fifteen times cheaper than copper. 

Nor do these estimates take into account the expense of maintaining metal and wooden roofs. 
Tin and iron require frequent paint to prevent rust. Shingles require paint to prevent rot. Copper 
requires frequent soldering at the joints to keep the roof from leaking. A slate roof, when properly 
put on, is practically permanent and requires comparatively no repairs. 

Among the notable buildings roofed with Peach Bottom slate, from all of which the same favor¬ 
able reports have been gathered relative to wearing qualities, absence of repairs and unfading color, 


U. S. Government Buildings,.Pittsburg, Pa. 

.West Point, N. Y. 

. ..Brooklyn Navy Yard, N. Y. 

.Washington Navy Yard, D. C. 

.Annapolis Naval Academy. 

.Tybee Island, Ga. 

.Fort Point, Galveston, Tex. 


.Spokane Falls. 

National Soldiers’ Home, .Danville, Ind. 

Philadelphia Hospital for the Insane, .Philadelphia, Pa. 

Western Pennsylvania Penitentiary, .Pittsburg 1 Pa 

“ “ Hospital. “ <* 

Allegheny County Workhouse, . “ 

Warren Insane Asylum, .Warren 


42 
















Danville Insane Asylum, ...Danville, Pa. 

Huntingdon Penitentiary, .Huntingdon, “ 

City Market House,.Lancaster, “ 

City Market House,.York, “ 

Orphans’ Home, . “ “ 

County Court House,. “ “ 

Maryland State Insane Asylum Buildings, (near) .Baltimore, Md. 


Maryland House of Refuge Buildings, (near) . 
Maryland House of Correction Buildings, (near) 

Maryland State Penitentiary, . 

Maryland State Normal School, . 

Enoch Pratt Free Libraries,. 

Notre Dame Academy (near) . .. 

Johns Hopkins University Buildings. 

Sheppard-Pratt Insane Asylum Buildings, (near) 


B. & O. R. R. Grain Elevator,. 

Pennsylvania Railroad Grain Elevator, . 

Poole & Hunt’s Foundries,. “ 

Gas Works, . 

Maryland State Insane Asylum Buildings, .Mt. Hope, 

“ Agricultural Buildings, ...College Park, “ 

New Jersey State Insane Asylum,.Morristown, N. J. 

State Hospital for Insane, .Poughkeepsie, N. Y. 


The 

Story 

of 

Slate 


43 

























The West Virginia Hospital for Insane,.Clarkesburg, W. V a. 

Story Lenox Library, ..New York City, 

of Carnegie Library,.Allegheny, Pa. 

Slate York Collegiate Institute, .York, Pa. 

Ursuline College, .Pittsburg, Pa. 

Episcopal Home, .Pittsburg, Pa. 

Presbyterian Hospital Buildings, .Philadelphia, Pa. 

Kirkbride Hospital Buildings, . “ “ 

Pennsylvania Railroad, Broad Street Station,. 

Round House and Shops, .Altoona, Pa. 

“ " Shops, .Wall Station, Pa. 

“ “ " .Mt. Royal, Md. 

Freight Houses, .Chicago, Ill. 

Passenger Station, .York, Pa. 

“ “ “ “ .Trenton, N. J. 

B. & O. R. R. Shops,.Mt. Clair, Md. 

Cambria Iron Companys Buildings, .Johnstown, Pa. 

Westinghouse Shops and Buildings,.Wilmerding, Pa. 

Billmeyer, Small Co.s Car Shops,.York, Pa. 

Gas Works, (Point Breeze), .Philadelphia, Pa. 

..Pittsburg, Pa. 

..Newark, N. J. 

(Metropolitan), .New York. 

..Boston, Mass. 


44 

































'il. fr ■ • / . i. > ■ ■ ii : , iy■ ■ : 


- 


— 


t. 


The 

Story 

of 

Slate 


Probably there is no more striking example of the indestructibility of Peach Bottom roofing slate 
than the roof which surmounts that rambling old landmark, the old Ramsey Tavern on Peach Bottom 
ridge. The slates are unbroken, their color has not faded and their weather resisting qualities are not 
impaired. The old Ramsey Tavern is a monument to the “BEST SLATE IN THE WORLD.” 







































































































The P rudential Insurance Company, Building, (general offices).Newark, N. J. 

Story Residence, Geo. Vanderbilt, Esq., (Biltmore), .Asheville, N. C. 

of Wm. B. Astor, (Fifth Avenue),..New York. 

Slate “ Hon. S. B. Elkins,...Elkins, W. Va. 

E. C. Camp, Esq., .Knoxville, Tenn. 







OTHER PENNSYLVANIA SLATES 


T HE slates of Pennsylvania, aside from those of the southeastern part of York County, which 
are described under the heading* “Peach Bottom” slate, occur in Northampton and Lehigh 
Counties in a strip from two to four miles wide, on the southern side of the Blue Mountain, 
extending from Delaware Water Gap to a point four miles west of Lehigh Gap, a distance 
of about thirty-two miles. The chief centres of the slate industry of Pennsylvania other than Peach 
Bottom Ridge, are at Bangor and Slatington. 

On the southeast, forming a belt between Easton and Reading and beyond are the granite-like 
rocks of South Mountain, flanked and dotted over with strips of hard, flint-like stone and sandstone. 
Still farther northwest is a slightly hilly belt of roofing slates from six to eight miles wide. At one 
cud these slates overlie the limestone, and at the other they dip under the Blue Mountain. The 
boundary between the slate formation and the limestone is roughly parallel to the general course of 
the Oneida and Medina boundary, but passes a little north of Nazareth. 

The commercial slate, however, comprises but a few hundred feet. “Ribbons,” or small beds of 
grit, measuring from a fraction of an inch to two feet in thickness, characterize this slate belt through¬ 
out. This grit consists mostly of more or less angular grains, together with scales of hard stony sub¬ 
stances that interfere to some extent with rapid work in the several quarries. The corrosive carbon¬ 
ates are also present to a greater or less degree. Commercial slate is obtained along two belts. The 
upper and northerly one, known as the “soft vein,” consists of beds, of relatively soft slate, of sufficient 
thickness between the ribbons to furnish large slabs suitable for mill stock or roofing purposes. The 
lower or southerly belt, the “hard vein,” consists of small beds of harder slate, separated by small rib¬ 
bons which are not coarse enough to interfere with their use either as mill stock or roofing slate, but 
makes the slates more difficult to quarry and as a result more expensive to bring to the surface. The 


The 

Story 

of 

Slate 


47 


The 

Story 

of 

Slate 


Bangor, East Bangor, Pen Argyl, Danielsville, Slatington and Slateclale quarries are in the “soft vein 
belt and the Belfast and Chapman are in the “hard vein.” 

In Northampton County the slate is dark gray, and to the unaided eye has a fine texture and a fine 
cleavage surface, but is almost without lustre. There is a gritty bed both at top and bottom which is 
regarded as the limit of the slate and the thickest bed of good slate is only nine feet thick, unlike 
Peach Bottom, which appears to be practically inexhaustible. 

The product from the large beds is used for roofing, but that from ribboned beds in the largest 
quarry in this county goes into mill stock exclusively and is not unfading. There is also in Northamp¬ 
ton County a six-foot bed of slate which is quite black, more so than any of the Lehigh County slates. 
It has to the unaided eye a somewhat fine texture and cleavage surface with a slight lustre. 

The quarries at Pen Argyl are regarded as being near the bottom of the “soft vein” belt. One 
measures 650 feet long, 600 feet across and 300 feet in depth. It is a clay slate, the chemical analysis 
of which points to rapid decay. There is an exceptional bed, however, forty-four inches thick, of a 
dark, slightly greenish gray slate of superior quality. The chie'f product of this quarry, however, is 
a very dark-gray slate which, to the unaided eye, has a fine texture and a rough, almost lusterless sur¬ 
face. Only a portion of it can be used for roofing slate. 

Some of the quarries at Pen Argyl show the passage of the black slate by weathering into a 
yellowish light brown, and even white shaly or flaky substance. The dumps afford specimens show¬ 
ing all gradations from black slate to white rock. In this connection it should be stated that in the 
“soft vein” quarries generally, judging from the dumps, the amount of iron and lime in the ribbon 
varies greatly. The slate flags which form the sidewalks in the village of Bangor wear along the rib¬ 
bons more rapidly than along the slaty portions. 

There is in this county a “hard vein” belt. The principal quarry measures from 700 to 800 feet 
long, and is about 200 feet wide and 300 feet deep. The largest bed, which, although containing very 

48 



Workmen clearing away the debris and ribboned 
slate in a quarry near Slatington, Pa., rn order to 
reach a thick workable bed of valuable slate. This 
condition does not exist on the Peach liottom ridge. 



The 

Story 

of 

Slate 


A remarkable fold of slate in a quarry near Slat¬ 
ington which shows a close “syncline” or trough¬ 
like, curled-up formation crossed by curved joints, 
over which are glacial deposits or “top.” 






The 

Story 

of 

Slate 



small ribbons, can be used for roofing slate, measures sixteen feet. The number of ribbons exposed 
on the east-northeast wall, where the fold opens out, is 112, averaging a little over two per foot of 
slate. 

The slate is very dark gray, but is crossed by frequent ribbons a trifle darker and measuring from 
one-eighth to one-half inch in^width. To the unaided eye it has a fine texture, slightly rough and 
slightly lustrous surface. 


The product of this hard vein was formerly used largely for flagging, posts, steps, etc., and because 
of its hardness had to be cut with diamond saws which operated horizontally. Owing to the competi¬ 
tion of sandstone flagging and the high price of diamonds, this outlet is closed and the product now 
is used exclusively for roofing slate, for which, however, only selected material is available. 

The slate quarries of Lehigh County all belong in the “soft vein" belt. The relation of the “soft 
vein" slate to the scaly formation of loose stone of similar formation is well exposed near Lehigh Gap, 
on the border of the county. On the eastern side of the gap the outcrop is a black Hake of loose stone 
that, however, is capable of being split like slate which occurs in alternating thick and thin beds. The 
thick ones weather into shell-like fragments, while the thin ones break up into pencil-like pieces. A 
hundred feet south of the locality described a slaty cleavage predominates. Therefore, within a space 
of 200 feet the transition from a shale to a slate can be observed. 

In weathering, the Lehigh slates undergo the same transformations as those of Northampton 
County. The black slate first passes into a soft, yellowish-brown rock, which later becomes nearlv 
white clay, the “shale clay" of the fire-clay pits. 

The slate quarries of Lehigh County are now confined to an area comprising about three square 
miles along Trout Creek arid its tributaries. This stream empties into the Lehigh from the west at 
Slatington. The older quarries have reached a depth of about 300 feet. 

The Slatington slate is a dark, bluish gray. After prolonged exposure this slate becomes at first 


50 



An unusual curled-up formation or syncline of 
sea-green slate at West Pawlet, Vermont. The 
slate within which is usually broken up and almost 
valueless, except for the smaller sizes of roofing 
slates. 



The 

Story 

of 

Slate 


Formation of slaty rock crossed by veins of 
quartz, (hard, flinty and semi-transparent rock), 
which appears at intervals in the green slate of 
New York and Vermont. 






I 


The a li ghter gray and finally various shades of cream and coffee color, but the rapidity and degree of dis- 
Story coloration differ in different beds. These slates are best adapted for blackboards and other indoor 
of obj< 

Slate 


VERMONT 


N r EXT in importance from the viewpoint of commercial slate is Vermont, in which there are 
at least four distinct slate districts. The most easterly extends along the Connecticut 
River for more than two-thirds the length of the State. The slate is black or dark gray, 
and has been worked in Guilford, in Windham County, at the extreme southern end of the 
State, and also in Thetford, in Orange County, and at Waterford, in Caledonia County. The next 
district extends along the east flank of the Green Mountain range from the Canada line to about the 
middle of the State, and has been extensively worked at N T orthfleld, in Washington County. The most 
important district, which furnishes the well-known “green" and “purple" slates, lies between the 
Taconic range and Lake Champlain, extending from the town of Sudbury, in Rutland County, south¬ 
ward to Rupert, in Bennington County, a distance of twenty-six miles. This belt also passes into 
Washington County, N. Y., where, however, it has thus far proved of less economic importance. The 
fourth is black slate, as yet undeveloped, and covering only from ten to twelve square miles in the town 
of Benson, in Rutland County, near Lake Champlain. Vermont slate, as a rule, contains but little 
carbonate, which indicates excellent wearing qualities. Records, however, show that the Peach Bot- 
ton slate of Pennsylvania possesses these qualities to a far greater extent. 

The factor of waste is extremely large in quarrying Vermont slate and an important quarry near 
Montpelier is said to have been abandoned some years ago for this reason. This quarry was oper¬ 
ated by means of three wide openings at intervals and communicating with each other by a ten-foot 
open cut, which also served as a drain. This waste, may have been the result of the complex opening, 
as the slate appears to be essentially the same as that of the Northfleld quarries, which are worked 
with a percentage of waste (between 70 and 80 per cent.) that is not excessive when it is recalled that 
the old fashioned methods of quarrying is the vogue. 


The 

Story 

of 

Slate 


53 



The 

Story 

of 

Slate 


Tt is Western Vermont that furnishes the green and purple roofing slate, while a commercial red 
slate is quarried near the boundary line between Vermont and New York. This bed continues into 
the last named state in the vicinity of Granville and Hampton. In some parts of Western Vermont 
two separate beds of slate, distinct both in color and quality twist around each other, sometimes one 
quality appearing on top and then the other. While this condition is at times puzzling, the relations 
of the two beds are more intricate in New York than in Vermont. The purple slates sometimes 
contain a few inches of dark-red slate. There is also some difference in the shade of the different beds 
of green in the same quarries, some being more green, others more gray. There are also differ¬ 
ences in the amount of discoloration, produced by weathering in beds of the same locality. Although 
some quarries produce only the so-called “unfading green" and others only the “sea green,” these differ¬ 
ences appear not to belong to strata or deposits of different ages, but to occur at different points' in 
strata of the same period. 

The relations of the “sea green" and the “unfading green” are not at all clear. There is nothing 
as yet to show that the positions of these two varieties of slates are not identical. It seems probable 
that, at a point within two miles north of Poultney, a change in the sediments occurred, sufficient to 
account for the change in color and durability. Whether this alteration in composition is alone suffi¬ 
cient to account for the difference is uncertain. There may have been some change in the resistance to 
pressure which would account for more perfect cleavage at the south than at the north, or possibly, the 
greater abundance of grains of quartz, (hard, flinty stone), at the north may be responsible for the 
altered structure. With more lime deposited at the south and more quartz sand at the north, the 
whole difference may be traced back to changes in sediment. Even this demarcation between the fad¬ 
ing and unfading green slate areas is not absolute, for fading green slates occur well within the unfad¬ 
ing green area. The purple slates frequently have green ribbons—an inch or two in thickness, and 
such ribbons run into tows or planes of green'spots. The ribboned slates arc used for flagging. 


54 




The 

Story 

of 

Slate 


Syncline or peculiar trough-like folding or curling up of a bed of black and gray banded slate at 
West Castleton, Vermont. This unusual formation shows the effect of the natural wearing away of the 
softer portions of the slate. This twisted, curled or trough-like effect is considered by many authorities 
to be a faulty formation that adds to the expense of quarrying. Such faults are not found on the Peach 
Bottom ridge. 





The 

Story 

of 

Slate 




i 


In the unfading green-slate portion of the belt, about one and one-quarter miles north of Homo- 
seen and a little east of the lake, is an abandoned quuarry where green slate which were made into 
slate pencils were obtained. The general substitution of paper tablets for school slates, however, has 
almost stopped the manufacture of slate pe'ncils. 





if*- 


* 


5b 



» 




MAINE 


T HE slate region of Maine lies about in the centre of the State, in the southern part of Pisca¬ 
taquis County, south and southeast of Moosehead Lake and east and west of Sebec Lake, in 
the towns of Monson, Blanchard and Brownville. Commercial slate occurs also in the town 
of Forks, Somerset County. The portion of this belt now yielding commercial slate lies 
south of the central granite area of the State. The general structure of this belt is unknown. 

Three quarries are in operation in the town of Monson. The slate is dark gray, hut at the surface 
some of the beds have in bright sunlight a slightly purple hue, hut is almost lustreless. 

At another quarry, three and one-half miles from the village, there are about thirty feet of slate 
and interbedded flint exposed. The thickest bed of slate measures about eight feet. The slate is dark 
gray; to the unaided eye has a finer texture and finer cleavage surface than that of the first mentionel 
quarry, and also more lustre. At the third quarry a bed of black slate nine feet thick, with a bed of 
flint fifteen feet thick on its north side, and small alternating beds of hard stone and slate on its south 
side are exposed, the whole series measuring perhaps fifty feet. As only one bed of slate is worked, 
the percentage of waste at this quarry is comparatively small. It has some lustre. This slate is 
used both for roofing and mill stock and particularly for electric purposes. 

There are two quarries at North Blanchard, the slate from these quarries is also a dark gray, 
with a slightly lustrous surface. Only one quarry is now in operation at Brownville, which lies less 
than a mile northeast of the station. Here are exposed forty-two beds of slate alternating with as 
many of flinty rock and measuring altogether 165 feet in thickness. The slate beds range from six 
inches to six feet, and the rock beds from six inches to five feet six inches. At an abandoned quarry 
in the same vicinity there are twenty-eight beds of slate alternating with an equal number of flinty 
rock, measuring in all 161 feet 6 inches. The slate beds range from one to nine feet and the rock from 


The 
Story 
of . 
Slate 


57 


The 

Story 

of 

Slate 


four inches to twenty feet in thickness. The Brownville slate is highly crystalline, and is said to he 
one of the most valuable slate districts in the United States excepting Pennsylvania. 

A slate prospect opened in Forks, Somerset County, is about eighteen miles west of the North 
Pdanchard quarries, in the southwest corner of the town of Forks, the nearest railroad is the Somer¬ 
set Railway extension at Mosquito Narrows, six miles distant. The slate is bluish black, of good tex¬ 
ture and cleavage surface, with a lustre not so great as that of the Brownville slate. Neither the ledge 
nor the fragments, said to have been exposed fifteen years, show discoloration. This “Pleasant 
Pond” slate differs from the Monson slates in having a lustrous and smooth surface, and from the 
Brownville slate in having a little less lustre. It would prove suitable for roofing or mill stock pur¬ 
poses. Whether, like the other slates of the State of Maine, it is interbedded with hard flinty ribbons 
at frequent intervals, has not as yet been determined. 



58 





A ribboned slate from a quarry near Hatch 
Hill, in Whitehall, New York. Ribbons are sel¬ 
dom found in the best quality slates and are not 
of the same hardness as the marketable product. 



The 

Story 

of 

Slate 


A remarkable specimen of black roofing slate 
from a prominent quarry at Brownville, Maine. 
This fibrous formation is in the shape of long crys¬ 
tals and lias a wavy, uneven surface. 








MARYLAND 


The 

Story 

of 

Slate 


T HE Peach Bottom slate of Cardiff, in Harford County, about thirty miles northeast of Balti¬ 
more, extends up into Pennsylvania, and has therefore been considered under a heading of 
its own, particular attention being paid to the rich Pennsylvania-Maryland and the old Proc¬ 
tor Quarries which are equipped with up-to-date machinery. Slate occurs also in Mont¬ 
gomery and Frederick Counties, about forty miles west of Baltimore and thirty-three miles northeast 
of Washington, where it has been prospected and quarried to a small extent. This slate belt, whatever 
may be its exact bounds, is well exposed at Ijamsville, on Bush Creek, and the Baltimore and Ohio 
Railroad in Frederick County. Between Ijamsville and a point two and one-half miles southwest of 
that place, it is at least one and one-half miles wide, and reappears west of Hyattstown, three and one- 
half miles farther south in Montgomery County. It passes between Sngarloaf Mountain and the vil¬ 
lage of Mount Ephraim on the west and Hyattstown and Barnesville on the east, its minimum length 
and width being about twelve and one and one-half miles respectively. 


One-fourth mile west of Ijamsville station is an abandoned quarry of dark, slightly reddish-pur¬ 
ple slate. Similar slate but interbedded with light green, occurs also several hundred feet east and 
north of the station. On Little Bennett Creek, about a half mile from Thurston, in Frederick County, 
is another quarry, operated twenty years ago but now abandoned. The slate is also dark purple, with 
light-green passages containing here and there a scaly, bright-green mineral, in which is a trace of 
copper. A piece of this slate that is said to have been on a roof many years shows some lightening 
of the color, owing chiefly to the growth of lichens, but the change is only superficial. 


About 600 feet from this and one-half mile from Thurston is a recently opened quarry. Some 
of the slates on exposure develop dark spots, due to the organic change of some mineral. 


60 


VIRGINIA 


I N reports to the legislature of Virginia, attention was called to the slate deposits east of the 
Blue Ridge in Buckingham, Fluvanna and Fauquier Counties. Slate also occurs in the Blue 
Ridge in Amherst County. This roofing slate makes its appearance on both sides of the 
James River. In Buckingham County the bed is largely exposed in the neighborhood of New 
Canton, on Slate River. This quarry was first opened to procure slate for roofing the Capitol, but 
little further use has been made of it. 

Slate River empties into the James about forty miles west-northwest of Richmond and fifty-two 
miles northeast of Lynchburg. The width of the formation north of the James extends from a point 
one-half mile west of Bremo Bluff to a small creek entering the James to the southeast. South of the 
Janies its eastern boundary lies about .3,000 feet west of the toll bridge opposite Bremo Bluff, and its 
western boundary is roughly one-fourth mile east of the Virginia Mills, on Slate River. There is 
in this vicinity a forty foot bed of slate. 

The general structure of the belt in which the commercial slate beds lie, judging from the rail¬ 
road cuttings between New Canton and Slate River, appears to consist of minor folds. The com¬ 
mercial slate itself appears to occupy a belt two-fifths of a mile wide along Hunt’s Creek, which is 
a tributary of Slate River. At Arvonia the river’s course is, roughly, like that of Hunt’s Creek. 
There appears thus to be a bend in the slate beds between Arvonia and the north side of the James. 
The quarries near Arvonia are scattered along the sides of Hunt’s Creek for a mile northeast of that 
place. The quality of the slate is said to be fair. It is a dark gray, with a slightly greenish hue. 
To the unaided eye it has a rough, lustrous surface. 

The Snowden slate deposit is on the southeast side of the Blue Ridge, north of the cut through 
which the James River flows. It is situated about eighteen miles from Lynchburg. The slate crops 


The 

Story 

of 

Slate 


61 


The 

Story 

of 

Slate 


out in a valley of Rocky Row Mountain on its northwest side and a spur of Big Piney Mountain on its 
southeast side. The general structure and the actual relations of the slate have not yet been com¬ 
pletely investigated. 

There are several prospects in the neighborhood of White Sulphur Springs on the Rappahannock, 
six miles southwest of Warrenton, from which roofing slate was obtained as early as 1837, but they 
have never been worked systematically. The slate is black, and to the unaided eye, has a coarse tex¬ 
ture, a rough speckled cleavage surface with little lustre. The odor of clay is also present, and scien¬ 
tists say it is a clay slate. Other smaller beds of slate have been prospected. In one the slate is 
bluish black, has a coarse, crystalline texture, and a knotty, wrinkly surface. The surface has very 
little lustre, but the clay odor is much in evidence. The iron and sulphur noted in all these Fau¬ 
quier County slate prospects and the sulphurous character of the springs, are probably intimately 
related. The indications from the openings and the microscopic examinations are not sufficiently pro¬ 


mising to warrant investments. 


62 


NEW YORK 


T HE slates of Washington County, N. Y., are a continuation of those of Rutland County, Vt. 

They are green and purple, like those in Vermont and were once extensively quarried at 
Middle Granville and Jamesville. 

While the green and purple slates are at present quarried almost exclusively on the Ver¬ 
mont side of the boundary, the red and green slates attain their best development on the New York 
side, particularly in the towns of Granville, Whitehall and Hampton. Beds of red and green slate 
alternate vertically, and overtop each other. The thickness exposed at the quarries, reaches fifty to 
seventy-five feet, mostly red, with about twenty-five feet of green overlying; but taking away that 
which is too hard or too soft or badly veined, there are sometimes but ten feet, rarely more than 
twenty-five feet, of good red slate exposed at any one quarry, although it sometimes reaches a total of 
forty-two feet. A few feet or inches of dark red or purple sometimes occur in the red. Beds of 
greenish quartzite bordered bv a purple slate, the whole “ribbon” measuring an inch or two in thick¬ 
ness, are not uncommon. Both red and green slates are frequently speckled. 


The 

Story 

of 

Slate 


The “red” slate is a decidedly reddish-brown, becoming brighter on exposure. To the unaided 
eye its texture is fine, and its surface varies from slightly rough to speckled, with minute “eyes” or 
“knots,” in either case without lustre. There is also present a noticeable odor of clay. Distributed 
throughout the slate are many bright-red dots or spots of circular or irregular oval outline. 

The slate is usually interbedded and passes into a light bluish-green slate, brighter in color 
than the “unfading green” slates of Vermont. Its color is peculiarly bright by lamplight; its tex¬ 
ture and surface are similar to those of the “red” and the surface is also sometimes speckled. It is 
said to be unfading. ' 


6 3 


The Black Roofing slate was quarried many years ago, in a small way, three miles south of Hoosick 

Story Falls, near Hoosick, and also, at a later time two miles south of Stephentown, near Lebanon 
of Springs, in Rensselaer County, N. Y., but did not prove to be of economic importance or commercial 

Slate value at either locality. 



% 


64 



The 

hands 


photograph shows slate alternating with 
of uncleft rock, in llupert, Vermont; near 
I he New York line. A striking example of slip or 
false cleavage, seldom seen in tlie Pennsylvania 
quarries. 



This interesting and unusual photograph shows 
a bed of sandstone or shale weighing many tons, 
resting on a valuable bed of green slate at Eddy 
Hill, Fairhaven, Vermont. 





CALIFORNIA 


The 

Story 

of 

Slate 


T HOUGH roofing slate has at different times been quarried on a small scale in other parts of 
California, the only important slate-producing area in the State is located in Eldorado 
County. The quarries which have been opened in this district arc located northwest of 
Placerville, at distances of from one to six miles from that town. At present the most im¬ 
portant quarry is near Slatington, and this is now being worked on a large scale but with the old, 
time-worn methods. The slate shows rather frequent, but narrow, “ribbons." These ribbons are 
bands (from one-sixteenth to one-half inch thick usually, occasionally as thick as two inches) of 
material differing in composition from the mass of the slate. They do not furnish merchantable ma¬ 
terial. 

The product is a dense, deep-black slate, splitting finely and regularly, with a smooth, glistening 
surface, much like that of the Bangor and Lehigh slates of Pennsylvania. The frequency of the rib- 
bons and other faults prevents the slate from being serviceable as mill stock, but as a roofing material 

it is fair. A band of green slate several feet wide, crosses the main body of black slate. ()n examina¬ 
tion it is found that the borders of this band are not parallel to the “ribbon” of the black slate. 

The green band can not, therefore, be interbeddcd with the black slates. The probability that it was 

originally a hard rock which has been changed to a slate by pressure, is strengthened by chemical 

analysis. 

* 

The “green slate" is in reality gray-green in color. It splits readily, though with not so smooth 
a surface as the black slate. It stands punching and trimming well, and is sufficiently strong for 
roofing use. Considering its origin and composition, it is probable that it will be a highly durable 
slate, holding its color well. At present it is sold entirely for trimming and lettering on black slate 
roofs, for which purpose it is well adapted, giving pleasant color contrast, A quarry located about 

66 


three miles north of Placerville-Kelsey stage road is the oldest slate quarry in the district, having 
been opened about twenty years ago. It has been shut down since 1897. Several openings were 
made in a bluff forming the river hank at this point and in the easternmost of these openings, a rather 
poor slate with irregular points is shown. The western opening is quite small, with a tunnel which 
was apparently run in on a hand of better slate. The slate piled in the yard has kept its color fairly 
well. It seems possible that this quarry may be flooded at high water and it is badly located, having- 
no large dumping area available near the quarries. The quarry has not been worked deep enough to 
get really good slate. Still another quarry has been opened on the north side of the river and west of 
the Placerville-Kelsey road. It has been abandoned since 1897. A large stock of trimmed slates is 
still piled in the dressing yard, and many of these have already discolored badly. 

The Eldorado County slates have practically no competition on or near the Pacific coast, and there 
has recently been large shipments to Hawaii and Guam. Until recently the principal problem has 
been the transportation of the slates from the quarry to the railroad. An aerial tramway system from 
its quarry to a point near Placerville is now in use and is apparently giving satisfactory service. This 
tramway is an engineering feat of no mean order, the crossing of the South Fork of American River 
being the principal difficulty encountered and successfully overcome. 


The 

Story 

of 

Slate 


ARKANSAS 


The 

Story 

of 

Slate 


T HE slate deposits of Arkansas are included in an area of prehistoric rocks in the west-central 
portion of the State. This area is about 100 miles in its greatest dimension from east to 
west, and varies from twelve to twenty miles in breadth from north to south. The towns 
of Little Rock, Benton, Malvern, Hot Springs and Mena are all located just outside the 
boundaries of this area. Within this district deposits of roofing slate occur at numerous localities, 
but outside of its limits no slate can reasonably be expected to occur in Arkansas. This should not 
be construed as meaning that all this area is underlain by deposits of roofing slate, for such is' by no 
means the case. On the contrary, workable roofing slate deposits make up only a small portion of it, 
the remainder being occupied by sandstones and shales. 


Within the district noted roofing slates have been worked in a small way at several points near 
Hot Springs, Garland County, for a number of years. None of the workings, however, has been 
extensive enough to give a definite idea of the commercial possibilities of the deposits. 


During the last few years a new slate area has been exploited in western Arkansas, the principal 
deposits being in the counties of Polk and Montgomery. Black, gray, red and green slates occur in 
abundance and a number of companies have been organized to work various properties. The black 
slate quarry is located on Crooked Creek, and is a fine-grained, deep black. It seems excellent for 
either roofing or mill slate. A few beds of rock (sandstone) are included in the section. But alto¬ 
gether a thickness of about 400 feet of black slate is exposed in a quarry near Crooked Creek. 


Northwest of this quarry is one where most of the slate exposed is green, with occasional red 


68 




The 


Story 



Difficulties that must be overcome in an important slate quarry at Brownville, Me. The photo¬ 
graph shows the pit in which are forty-two beds of slate alternating with an equal number of fissile 
sandstone known as quartzite. The wall to ^the left is almost a solid bed of this peculiar sandstone 
held together by the natural mineral cement of quartz. 







The streaks. The slate on the dump has disintegrated very badly on weathering, and is really hardly more 
Story than a clay shale. 

of Summarized there is a pure black slate near Big Forks which to the unaided eye has an exceed- 

Slate ingl v fine texture and a remarkably smooth cleavage surface with a slight lustre. This seems to be a 
superior roofing slate, with a fine cleavage and not liable to discolor on exposure, but its strength and 
its behavior under frost has not been thoroughly tested. There is also a dark-red slate deposit near 
Big Forks. In color this slate is somewhat darker than the “red” slate of New York. It is speckled 
and almost lustreless and has an odor of clay. This slate compares favorably in texture with the New 
York “red" slate. There is also a red slate in Mammoth red and Lost Hannah beds. Color lighter 
than above, but not quite so red as the New York slate. To the unaided eye it has a fine texture and 
a fine cleavage surface, but no lustre. It also has a strong odor of clay. It is a finer and softer 
slate than the dark red, but has not been thoroughly tested for strength and frost resistance. A green- 
gray slate at Mena resembles in color the “sea-green" slate of Vermont. It possesses a waxy lustre 
and also possesses the odor of clay. 


7C 


GEORGIA 

T HE workable roofing- slate deposits of Georgia arc developed only near the town of Rock- 
mart, Polk County. The most extensive slate quarries in the United States south of Penn¬ 
sylvania are located at Rockmart. The formation in which the quarries are located extends 
across the border into the Rome quadrangle, but it is not certain that any workable slate 
will be found in this area. The formation is variable in composition, and to the north of Rockmart 
consists largely of unaltered clay shales with beds of limestone and sandstone.* 

Commercial considerations in connection with the slate industry, make slate a very important pos¬ 
sible source of cement material. Good roofing slate is relatively scarce and commands an excellent 
price when found. In the preparation of roofing slate for the market so much material is lost during 
sawing, splitting, etc., under the older methods, that only from ten to twenty-five per cent, of the 
amount quarried is salable as slate. The remaining seventy-five to ninety per cent, is of no ser¬ 
vice to the slate miner. It is sent to the dump heap and is a continual source of trouble and expense. 
This material, however, is often admirably adapted for use in connection with limestone in a Portland 
cement mixture. This is one of the plans now being carried out at the Pennsylvania-Maryland and 
the Proctor Quarries on Peach Bottom Ridge. 

Only one American Portland cement plant in Georgia is at present using slate as one of its raw 
materials, and this plant is of recent construction. It is located about half a mile east of Rockmart, 
Ga. The Portland cement manufactured there is made from a mixture of pure limestone and slate, 
both of which materials occur in the immediate vicinity of the plant. 

East of the town the surface rock is the “Chickamauga limestone," which has been quarried at 
several points in the vicinity and burned into lime. A cement company has purchased the property of 
the old Georgia Slate Company, about half a mile southwest of Rockmart, and carried on extensive 


The 

Story 

of 

Slate 


7 1 



The operations with the diamond drill. The intention was to quarry the slate, sell as slate the portions 
Story best suited for that use, and utilize the scrap and waste in the manufacture of cement. The quarries 
of from which the limestone is obtained are located half a mile east of town, near the mill. 

Slate 



72 







TENNESSEE 

S LATE deposits occur in eastern Tennessee, notably southeast of Knoxville. Two formations in 
this region contain beds of slate—the “Wilhite” and “Pigeon” slates. The Wilhite slate in 
the vicinity of Little Tennessee River, is too soft for commercial use, but has the necessary 
hardness and evenness, along Little Pigeon River. Along this stream the slate is well exposed 
over great areas, but has never been developed. Quarries have been opened in the “Pigeon” slate 
along the Little Tennessee River at many points, and slates and flags taken out for local use. The 
slates are fine, even grain, and split into slabs an inch thick, of any desirable size, or into roofing 
slates. That this slate resists weathering is proved by the high, sharp slate cliffs that border the river 
along most of its course. 





The 

Story 

of 

Slate 


73 


UTAH 


The 

Story 

of 

Slate 


F OR some years past a small amount of slate has been annually quarried, chiefly for samples 
and trial shipments, at various points in Utah. Deposits of slate, believed to be of work¬ 
able extent and of fair quality, have been described as occurring on the islands in Great Salt 
Lake, and some attempt has been made to develop these deposits. 

The locality which has been most widely discussed, however, is that near Provo. The slate 
deposits occur about two miles from Provo station, in Slate Canyon. The slate covers a considerable 
area, but that exposed at the surface is so badly broken up that large slabs can not be obtained. The 
Provo deposits furnish green and purple slates, the latter being apparently present in greater quantity. 
The green slates show little tendency to cleavage in their surface outcrops, and will probably be less 
satisfactory for roofing purposes than the purple. The green slates rub very smooth, however, and 
make good slabs or mill stock if obtainable in masses of sufficient size. 

The purple slates split well, with a surface almost as smooth as that of Peach Bottom (Penn- 
sylvania-Maryland) slate. From samples seen it appears that they also bear punching well, but as 
a commercial enterprise the quarries are still in embryo. 


74 



The William Quigley place, near Delta, Pennssyl vania, roofed with Peach Bottom slate, has with¬ 
stood storm and sunshine for sixty-live years and, as far as can be learned, has cost nothing for repairs 
during that period, except the replacing of some nails that originally held the slate in place and cor¬ 
roded so badly with the lliglit of years that new ones were driven to hold the same slates in position. 













































































ARIZONA 


1 I 



SPECIMEN of roofing slate recently received from Arizona by Dr. David T. Day, of the 
division of mineral resources of the United States Geological Survey, came from a deposit 
about six and one-half miles north of Phoenix, which is said to measure from 800 to 1,000 
feet in width* and about 5,000 feet in length. Its examination has yielded the following 
results: 

It is a bluish gray with a lustrous surface, marked by two sets of minute wrinkles that lie at right 
angles to each other. It has a marked odor of clay. If properly cut with reference to the direction 
of weakness this may prove a serviceable slate. 





76 


WEST VIRGINIA 


T HIS recently prospected slate district lies near Martinsburg in Berkeley County. This belt lies 
about thirteen miles west of the Blue Ridge and mostly on the western side of Opequon 
Creek, a small tributary of the Potomac. It measures at least fourteen miles in length and 
from two to three miles in width. This clay-slate formation, estimated at from 700 to 1,000 
feet in thickness, is in a series of folds. The rock is generally dark-gray, weathering into a yellowish 
or white clay, known locally as “soapstone.” The beds are small and are separated by darker rib¬ 
bons. The thickest bed exposed measured three feet six inches. A diamond drill core down to forty 
feet below the bottom of the quarry shows several three-foot beds. The slate is black, with a slightly 
brownish hue. The texture is somewhat fine and the cleavage surface rough without any lustre what¬ 
ever. It is proposed to use the product of this quarry for mill stock, for which it seems better adapted 
than for roofing. 

Clay-slate has also been found two miles from Middleway; in a brook southeast of Martins¬ 
burg, and also three miles southeast of Martinsburg, and it will be found in many other places. They 
are all clay-slates. The material can therefore hardly possess sufficient fissility or prove sufficiently 
strong or elastic to compete with mica-slates for roofing purposes. Furthermore the mode of weather¬ 
ing by the outcrops indicates its probably discoloration on prolonged exposure, so that it belongs in the 
“fading” group of clay-slates. 


The 

Story 

of 

Slate 


* 


77 


NEW JERSEY 


The 

Story 

of 

Slate 



HE Bangor-Slatington slate belt of Pennsylvania is prolonged eastward into New Jersey and 
roofing-slate quarries have been opened at several points, notably near Newton and Lafay¬ 
ette. The characteristics and properties of these slates will be found under the heading of 
“Other Pennsylvania Slates.” 



78 



Quarryiueii at Pinorwic, North Wales, “Dressing," “Splitting" and “Pillaring" in the old way. 
This is one of the one thousand groups of workmen to whom are sold portions of the quarry called 
“bargains" or lots IS feet wide and the height of the gallery (To feet) which they work together and 
divide equally the proceeds. This is a part of the system in the Welsh quarries. 


The 

Story 

of 

Slate 








MINNESOTA 


The 

Story 

of 

Slate 



EPOS ITS of roofing slate occur in northern Minnesota, a few miles west of Duluth. At pres¬ 
ent, however, all the quarries formerly opened have been abandoned, and the quality of the 
slate, as seen in specimens on the old dumps is hardly such as to justify reopening. 


The accompanying table shows the principal characteristics of thirty-eight kinds of slate as far as 
these bear upon economic or commercial value. These slates are from Arkansas, California, Maine, 
Maryland, New York, Pennsylvania, Vermont, Virginia, and West Virginia. The column headed 
“strength" refers to the tests by Merriman. Microscopic texture refers primarily to the body of the 
slate. By “crystalline" is meant that the slate consists of interlacing and overlapping scales and fibres, 
and is, therefore, a mica-slate. Such a slate should have, other things being equal, greater elasticity 

4r 

and strength than one in which there is no such texture. The fineness or coarseness of this texture has 
a bearing upon the strength of the slate. THE PEACH BOTTOM SLATES, WHICH REALLY 
APPROACH A MICA SCHIST, ARE THE STRONGEST OF THE TWELVE KINDS OF 
AMERICAN SLATES TESTED. 



Clay-slates (Fading) Martinsburg, W. Va. 


r (A) (black) 


(Fading) 


-< 


(B) (green) 

(C) (purple) 


r 


Mica slate < 


(Unfading) ^ 


(A) 


(B) 


(C) (green) 

(D) (purple) 


V 


V. 


Lehigh and Northampton Counties, Pa. 
Benson, Vt. 


The 

Story 

of 

Slate 


“Sea green,” Vermont. 

Purple of Pawlet and Poultney, Vt. 

PEACH BOTTOM, PA., AND MD. 

Arvonia, Va. 

Northfield, Vt. 

Brownville, Monson, Me. 

West Monson, Me. 

Granville, Hampton, N. Y ; Polk County, Ark. 

“Unfading green,” Vermont. 

Purple of Fair Plavcn, Vt. 

Thurston, Md. 


Si 










The 

Story 

of 

Slate 


Locality. State. ( Color. 


reach Bottom . 

Pennsylvania- 

Dark blue-gray 


Maryland . 


Old Bangor, Northampton 

Pennsylvania . 

Dark gray . 

County. 



North Bangor, Northamp- 

do. 

do. 

ton County. 




do. 

do . 

Cray bed . 

do. . 

Dark green . 

Big bed, Northampton 

do. 

I) a r k gray, not 

County. 


blue. 


do. . 

Blue-black . 

bast Bangor, Northamp- 

do. 

Dark blue-gray ... 

ton County. 



Slatington, Lehigh County 

do. . 

do. . 

Chapman “hard vein” — 

do. 

Dark gray . 

Ah'rrill ‘Rrownsvillt* . 

Maine . 

do. 

Yorth Blanchard . 

do. 

do. 

Monson Pond, Monson ... 

do. 

do. . 

“Maine.” nf Mnnsnn . 

do. . 

do. . 

West Monson . 

do. . 

do. 

Northfield, Vermont Black 

Vermont . 

Dark gray . 

“Spa preen . 

do. . 

Gray-green . 

Purple of “sea green” — 

do. 

» 

Purple-brown . 


COMPARATIVE CHARACTERISTICS 

Compiled from Carious Authentic 


Lustre. 


Very bright . 

Almost none. 

do. 

do. 

do. . 

do. . 

None . 

Almost none. 

do. . 

Slight . 

1‘v'erv bright . 

Slight . 

Almost none. 

Bright . 

Somewhat bright 
do. 

Waxy . 

None ... 

8j 


Cleavage Surface. Microscopic Texture. 


Minutely granular 

Fine . 

do ..... 

Rough . 

Rough granular . 

Somewhat fine . 

Rough . 

Somewhat fine . 

do . 

Slightly rough . 

Fine . 

Rough . 

do . 

do . 

Fine . 

Fine . 

do. 

do. 


Crystalline, coarse . . 


Crystalline, fine 

do. 

do. 

do. 

do. 

do. 

do. 


do. . 

do. . 

Crystalline, very fine _ 

Crystalline, fine . 

Crystalline, fine, but par¬ 
ticles irregular. 
Crystalline, very fine _ 

Crystalline, fine . 

Crystalline, very fine _ 

do. . 

do. . 







































































































OF PRINCIPAL AMERICAN SLATES 

Sources and Personal Research 


Principal Minerals. 


Carbonate. 


=2 Strength, 
m pounds 

'S c per 

~S square 

23 inch. 

<1 


Muscov., quartz, graphite 
andalusite, magnetite. 

Muscov., earb., quartz, kaolin. 

Muscov., carb., quartz, kaolin ..... 

Muscov., carb., quartz, chlorite _ 

Muscov., carb., quartz, chlorite_ 

Muscov., carb., quartz, pyrite. 

Muscov., carb., quartz, carbon. 

Muscov., carb., quartz, pyrite, 
chlorite 

Muscov., carb., quartz, kaolin. 

Muscov., quartz, carb., pyrite . 

Muscov., quartz, magnetite, pyrite 
Muscov., chlorite, quartz, pyrite ... 
Muscov., quartz, chlorite, biotite .. 

Muscov., quartz, biotite, chlorite .. 

Muscov., quartz, chlorite, pyrite ... 
Muscov., quartz, pyrite, magnetite 

Muscov., quartz, carb., chlorite- 

Muscov., quartz, carb., hematite .. 


None . 

Quite a little _ 

Much . 

0.155' 
Q.4N 

4.38 

11,2(i0 

9,810 

Quite a little .... 

(lo. 

4.09 

7,150 

Very much . 



do. 



Much . 



do . 

4.23 

( 2.83- 

1 3.40 


Quite a little .... 

None. . 

| 9.4::0 

! 

9,880 

do 


do . 

0.52 


do . 


do . 


9,130 



Much . 

( 0.63- 
1 2.20 
( 0.50- 
! 0.71 

1 7,250 

1 

|. 



1 


8.3 


The 

Story 

— —. = Q f 

Slate 

Remarks. 


Very sonorous. First Prize, Crystal Palace Ex¬ 
position, London, as best slate in the world. 

Discolors on continued exposure. 

Do. 

Do. 

Do. 

Discolors on continued exposure. 

In ribboned slate from this quarry the percentage of 
quartz would be higher than in the rest. 

Discolors on continued exposure. 

Discolors less readily than any of the above Pennsyl¬ 
vania slates. 

Very sonorous. 

Very sonorous. 

Very sonorous. 

Very sonorous. 

Very Sonorous. 

Becomes brown-gray on continued exposure. 
Discoloration less pronounced than that of “sea green.” 








































The 

Story 

of 

Slate 


COMPARATIVE CHARACTERISTICS OP 


Locality. 

State. 

Color. 

Lustre. 

Cleavage Surface. 

Microscopic Texture. 


do. . 

Green-gray . 

1 

do. . 

i 

Rough . 

Crystalline, irregular . 

Purple of “unfading” — 

do. . 

Purple-brown . 

1 

do. . 

do . 

do 

do. 

Blue-black . 

Slight . 

Somewhat tine . 

Crystalline, fine . 

Thurston . 

Maryland . 

Dark purple . 

Very bright. 

Slightly granular . 

Crystalline, fine, particles 

Arvonia, Williams . 

Virginia . 

Dark green-gray .. 

Very bright . 

Minutely granular . 

irregular. 

Crystalline, irregular . 


do. . 

do. . 

do. . 

Granular . 

Crystalline, i r r e g u 1 a r, 
coarse. 

Crystalline, fine . 


do. . 

Dark gray . 

do. 

Fine speckled . 


do. . 

do. 

Almost none. 

Minutely granular . 

Crystalline, fine, irregular 
do. 

Granville and Hampton ... 

New York . 

Red . 

None . 

Fine or rough speckled.. 

do . 

do. . 

Bright green . 

do. 

do. 

Eureka, Eldorado County 

California . 

Dar 1 * gray . 

Bright . 

Fine . 

Crystalline, fine . 

Af nn 0 T>rkllr Pnnnt.V 

\rkansas . 

Black . 

Slight . 

Remarkably fine . 

Crystalline, extremely fine 

Crystalline, fine 


do. . 

Dark red . 

Almost none. 

Rough speckled . 

Mammoth Red and Lost 
Hannah, Polk County. 

do. . 

Red . 

None . 

Fine . 

do. 

do. 

Green-gray . 

Waxy . 

Rough . 

Crystalline, extremely fine 

do. 

menu, ruih vuuntj . 

M a m m 0 t h Red, Polk 
County. 

Polk County. 

Polk County. 

Southwest, Polk County.. 

do. . .. 

Light green . 

Almost none. 

Fine . 

do. . 

Dark blue-gray _ 

Slight . 

Fine . 

Crystalline, fine 

do. . 

Light gray . 

None . 

Rough . 

do. 

do. 

West Virginia _ 

Dark gray . 

Black, brown hue . 

Almost none. 

None . 

Rough spangled . 

Rough . 

Crystalline, coarse, granu¬ 
lar. 

Not crystalline or imper¬ 
fectly so, coarse. 





84 
























































































































PRINCIPAL AMERICAN SLATES—Continued 


Principal Minerals. 


Muscov., quartz, chlorite, carb., ... 

Muscov., quartz, chlorite, hematite 

Muscov., quartz, carb., pyrite. 

Muscov., chlorite, quartz, talc. 

Muscov., quartz, biotite, carb., 
carbon. 

Muscov., quartz, biotite, carb., 
pyrite. 

Muscov., quartz, pyrite, kaolin? ... 

Muscov., quartz, chlorite, kaolin ... 

Muscov., quartz, hematite, kaolin, 
carb. 

Muscov., quartz, chlorite, carbon, 
magnetite. 

Muscov., quartz, chlorite, carbon ... 

Muscov., carbon quartz, pyrite _ 

Muscov., hematite, kaolin, quartz, 

Muscov., hematite, kaolin, quartz, 
chlorite. 

Muscov., quartz, kaolin, chlorite ... 

Muscov., quartz, kaolin, chlorite ... 

Muscov., quartz, pyrite, carbon- 

Muscov., quartz, chlorite, kaolin ... 

Muscov., quartz, carbon, pyrite- 

Carb., muscov., quartz, kaolin, py¬ 
rite, carbon. 


Carbonate. 


Strength, 
pounds 
per 

square 
c m inch. 

< 


do. 

Much 

None 

Some 

do. 

None 

Little 

Much 


Some 

None 

do. 

do. 

do. 

do. 

do. 

do. 

Some 

Some 


little . 

1 0.42- 
l 0.56 

/ 0,410 

I 



1.27 






9,040 

9,850 









( 0.11 

I 5.11 
1.43 

0.98 

I 9,220 

1 

8,050 

than red, 
illy 

























1.11 

and 

over. 





85 


The 

Story 

of 

Slate 


Preserved nearly all its color on continued exposure. 
Do. 

Sonorous. Probably “fading.” 

Sonorousness moderate. 

Very sonorous. 

Do. 


Very sonorous. 

Becomes brighter on exposure. 
Said to be unfading. 


Strength and behavior in freezing and thawing should be 
tested. 

Do. 


Strength and behavior in freezing and thawing should be 
tested. 

Some staining from pyrite. 

Between a grit and a slate. 











































The 

Story 

of 

Slate 


THE IDEAL SLATE QUARRY 

F OR more than ten centuries the same methods of quarrying that were the vogue in the days of 
the first crusaders, have continued until the present year, when up-to-the-minute machinery 
is being installed in the rich Pennsylvania-Maryland and the Proctor quarries, on Peach 
P)Ottom ridge. At last the ideal quarry is here, although to obtain the results there was 
a stubbornly contested battle between the slate quarryman and the men who desired to bring twen¬ 
tieth century appliances and devices to assist in taking the slate from its bed. The quarryman stoutly 
maintained that the old way, the way his father worked, the way in which the great hole in the ground 
had paid dividends in the past, was good enough. Why were innovations necessary? Why disturb 
the lethargy that hung over the entire slate industry for aeons ? Why bring machinery into the 
peaceful lives of the quarrymen who were unused to its whirling wheels? The work of installing 
this machinery is not complete as this booklet goes to press, but the innovation has begun and will be 
pushed forward as rapidly as is possible; with sound engineering methods and technical knowledge 
that admits of no mechanical error. 

Each argument against new devices and appliances was met with sound lucid and straightfor¬ 
ward reasoning, and George J. Atkins, the well known engineer evolved a plan whereby the product 
of both the Pennsylvania-Maryland and the Proctor quarries could be brought to the surface, sawed 
to the proper sizes, split and shipped at a cost that is but a fraction of that necessary under the 
slower, more expensive and older methods. Mr. Atkins, working for J. G. Feist & Company, of 
Harrisburg, Pa., at once began to revolutionize the methods of quarrying the slate and little by little 
the changes met with the approval of even the hard-headed, unimaginative quarrymen. Steel cables, 
each controlled by its individual hoisting apparatus stretch across the mouth of the quarry, and 
buckets of slate whirl to the surface with accelerated speed. A narrow gauge double track railroad 


86 



The 

Story 

of 

Slate 






























The 

Story 

of 

Slate 


i i 


is laid around the pit and the puffing locomotive will replace the old hand cars. The tracks are designed 
to carry away the now small item of waste to the dumping grounds at the same time that the useful 
blocks of slate are conveyed with equal speed to the manufacturing plant, which includes buildings 
both for the roofing and the structural departments. 

This railway at the Proctor quarry crosses the trestle over the old wagon road and spurs carry 
the cars to the machine and blacksmith shops, tool house and compressor room and the engine and 
car house, while the main line leads directly to the manufacturing department. The roofing plant, 
which is reached first, is designed with a steel frame having side walls and roof of slate, the equip¬ 
ment consisting, in the beginning, of six saw tables with multiple or “gang” saws specially designed 
to saw the great blocks lengthwise and then across in regular sizes for the roofing slate. These 
blocks are then carried to the splitters on moving belts in order that no time is wasted by these men 
in carrying the blocks a distance. They now devote their entire time splitting the slate. When their 
work is completed the finished slate is stacked in buckets and carried under a movable crane that 
glides easily on overhead rails, to the storage yards, where boys arrange the slate in packages ready 
for shipment. 

The saving in this department alone is of considerable importance as a comparison with the old 
style method will show at a glance. The sawing of the slate with multiple saws is not only quicker 
(cutting thirty-six blocks at once, by cutting six strips lengthwise, then passing to the six cross-cut 
saws) but saves the enormous waste that could not be avoided under the old way. With these saws, 
there is absolutely no waste except the rough edges of the first quarried block. Next, almost half 
of the time the splitter was. occupied by carrying the blocks and finished product to and from his 
working stool. With the new devices of movable conveying belts that bring the blocks to him and 
the big buckets under the traveling crane for carrying away the finished slate, he gives all his time 
to splitting slate and consequently does almost twice as much actual work during the day. 

88 



1 1 t 1 l 1 \ \ l \ l PEDESTAL TRACK PEDESTAL 

ttaaa*2222 

BTOQAGt VADD TQAVELINC* CCAML *««> 5LATE. BUCKET 

1 • CDAfil OOfO 200X200 

2- PAIL WAT u 

SCALE *4 inCH TO FOOT SCALE h INCH TO FOOT 


The movable crane and slate bucket that travels along overhead rails supported by steel pedestals 
and runs between the rooting and structural buildings and the big storage yards at the famous Proctor 
(Quarry on Peach Bottom ltidge. This bucket carries fifty squares of slate at once and the crane can he 
operated by one boy. It does the work of fifty men and accomplishes it far quicker and easier. 


The 

Story 

of 

Slate 































































rhe 

story 

)f 

Slate 


Again, the work of the trimmer is practically eliminated or done away with, for the blocks conic 
to the splitter exactly the size desired. The trimmer is useful now only for the purpose of cutting- 
down the slates to a smaller size where some flaw makes it unwise to use it the size originally cut 
by the saws. 

Next to the Roofing Department, the site for the building devoted to the manufacture of struc¬ 
tural slate is designed. This building will also have a steel frame, slate side walls and roof. The 
railroad tracks pass through the centre of the building and on either side of it are arranged large and 
small saw tables, a gig saw, planers and a rubbing or polishing table, together with ample storage 
and assembling space. This department is entirely new on Peach Bottom ridge and is designed to 
fill orders for various sized slabs used in structural or building work. Much of the slate that can¬ 
not be split to advantage for roofing use, owing tv) occasional faults, is excellent for this purpose 
instead of throwing it away as waste, such as has been done in the past. These blocks or slabs 
are useful for any purpose for which marble, granite or sandstone are utilized in the building trades, 
for mill uses, flagging, etc. 

Northeast of the structural department is the storage yard, arranged with alternating railways 
and elevated runways for the movable crane which carries the immense buckets of finished slate to 
the yards where they are stored until such time as they are shipped to the markets of the world. 

The several points in the manufacturing plant are all connected by railway and crane runs, while 
from the storage yards is an overhead tram to the freight siding of the M. & P. Railroad 3400 feet 
away. 


In the pit is placed the big steam shovel which has been used to level off the roads on the 
Proctor properties, and which now is utilized to clear away the debris and loose shale which is hoisted 
up in buckets, dumped in cars and carried to the dumping grounds. Each steel wire cable stretched 


90 





•The 

Story 

of 

Slate 

















































































































♦ 


* 


The across the quarry is operated and controlled as a unit from the small hoisting houses to the north 

Story of the pit and which as the quarry is enlarged will be moved back, with slight expense, 
of Throughout the plant electricity plays its part, and for the sake of economy, each individual ma- 

Slate chine is an electric unit and can be operated if necessary, while the remainder of the plant is still, 
thus obtaining the greatest efficiency with the least possible expense. 

Another contemplated improvement in the methods of working the old Proctor quarry, which 
will be installed as soon as the before mentioned machinery is working smoothly, is a series of saws 
that will cut away the slate in the quarries in huge galleries, thereby doing away with the present 
method of blasting the slate with dynamite, and which in itself wastes a percentage of good 
material. Expert engineers have computed that the saving of material and labor with the proposed 
equipment working satisfactorily will be about sixty-five per cent, of the gross; leaving an actual 
gross loss for waste of less than ten per cent, on the amount of slate taken from the quarry. 



92 


150 X 50 



House designed for the structural department at the Proctor Slate Quarry at Cardiff, Md. The 
equipment of specially designed machinery here includes large and small saw tables, gig saw, large and 
small planers and rubbing or polishing table together with ample space for storage and assembling. 


The 

Story 

of 

Slate 













































































































































































































































































































































































































. 






































